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Length of the diagonal - class-X

Description: length of the diagonal
Number of Questions: 47
Created by:
Tags: mensuration maths surface area and volume surface area and volume of cube and cuboid trigonometrical ratio and identities
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If the measures of the sides of a triangle are ________, then it is not a right angled triangle.

  1. $3,4,5$

  2. $5,12,13$

  3. $8,24,26$

  4. $7,24,25$


Correct Option: C
Explanation:

$\begin{array}{l} 8,24,26 \ \sin  ce, \ { \left( 8 \right) ^{ 2 } }+{ \left( { 24 } \right) ^{ 2 } }\ne { \left( { 26 } \right) ^{ 2 } } \end{array}$

Instead of walking along two adjacent sides of a rectangular field, a boy took a short cut along the diagonal and saved the distance equal to half of the longer side. Then the ratio of the shorter side to the longer side is?

  1. $\cfrac{2}{3}$

  2. $\cfrac{5}{3}$

  3. $\cfrac{4}{3}$

  4. $\cfrac{8}{3}$


Correct Option: D
Explanation:

Atp,

$\sqrt{l^2+b^2} + \cfrac{l}{2} = l+b$
$\sqrt{l^2+b^2} = b+\cfrac{l}{2}$
$l^2+b^2 = b^2+2lb+\cfrac{l^2}{4}$
$\cfrac{3l^2}{4} = 2lb$
$\cfrac{l}{b} = \cfrac{8}{3}$

$\angle B$ is a right angle is in $\Delta ABC$v and P,Q are points of trisection of hypotenuse $\bar{AC}.$ then $BP^{2}+BQ^{2}=\frac{5}{9}AC^{2}.$

  1. True

  2. False


Correct Option: A

In $\triangle ABC$ right angled at $B, AB=5\ cm$ and $\angle ACB=30^{o}$ then the length of the sides $BC$ is

  1. $5\sqrt {3}$

  2. $2\sqrt {3}$

  3. $10\ cm$

  4. $none\ of\ these$


Correct Option: A
Explanation:

Given:- $ABC$ is a right angled triangle in which $AB = 5 \; cm$ and 


$\angle{ACB} = 30°$

Using trigonometric ratio,

$\tan{C} = \cfrac{AB}{BC}$

$\Rightarrow \tan{30°} = \cfrac{5}{BC}$

$\Rightarrow BC = 5 \sqrt{3} \; cm$

ABC is a triangle, right-angled at B. M is a point on BC. Hence,
$AM^{2}\, +\, BC^{2}\, =\, AD^{2}\, +\, BM^{2}$
State true or false.

  1. True

  2. False


Correct Option: B
Explanation:

Given, $\angle ABC = 90$, M is a point of BC
In $\triangle ABM$, 
$AB^2 + BM^2 = AM^2$ (Pythagoras theorem)
$AB^2 = AM^2 - BM^2$ (I)

In $\triangle ABC$,
$AB^2 + BC^2 = AC^2$ (Pythagoras Theorem)
$AB^2 = AC^2 - BC^2$ (II)

Equating I and II,
$AM^2 - BM^2 = AC^2 - BC^2$
thus, $AM^2 + BC^2 = AC^2 + BM^2$

A guy wire attached to a vertical pole of height $18m$ is $24m$ long and has a stake attached to the other end. How far from the base of the pole should the stake be driven so that the wire will be taut?

  1. $15.87m$

  2. $16.8m$

  3. $15$

  4. $15.67$


Correct Option: A
Explanation:

Consider the wire and pole system as a right angled triangle such that length of pole is the perpendicular, length of wire the hypotenuse and distance between the base of pole and the stack is the base, such that, H = 24 m, P = 18 m
Now, from Pythagoras theorem,
$H^2 = P^2 +B^2$
$24^2 = 18^2 + B^2$
$576 = 324 + B^2$
$B^2 = 252$
$B = 15.87$ m
Thus, distance between the base of the pole and the stack is 15.87 m

The sides of a rectangular field are $80$ m and $18$ m respectively. The length of the diagonal is:

  1. $84$ m

  2. $98$ m

  3. $82$ m

  4. $86$ m


Correct Option: C
Explanation:

Given sides of rectangle are $80$ m and $18$ m.
Thus length of diagonal is $\sqrt{80^2\, +\, 18^2}\, =\, \sqrt{6 724}\, =\, 82\, $ m.

A person wishes to fit three rods together in the shape of a right-angled triangle so that the hypotenuse is to be $4:cm$ longer than the base and $8:cm$ longer than the altitude. The lengths of the rods are:

  1. $3:cm$, $4:cm$, $5:cm$

  2. $1.5:cm$, $2:cm$, $2.5:cm$

  3. $6:cm$, $8:cm$, $10:cm$

  4. $12:cm$, $16:cm$, $20:cm$


Correct Option: D
Explanation:

Let the altitude$=x:cm$
$\therefore$ The Base$=(x+4):cm$
and the Hypotenuse$=(x+8):cm$

Using Pythtegores Theorem
$(x+8)^2=(x+4)^2+x^2$
$x^2-8x-48=0$
$(x-12)(x+4)=0$
$x=12$
$\therefore$ The sides are $12:cm$, $16:cm$, $20:cm$ 

What is the value of the hypotenuse of a right triangle whose sides are $12$ and $18$?

  1. $4.24$

  2. $3.46$

  3. $2.16$

  4. $21.63$


Correct Option: D
Explanation:

Let the sides be $a=12$ and $b=18$

Le the hypotenuse be $c$
Using Pythagoras theorem
${ c }^{ 2 }={ a }^{ 2 }+{ b }^{ 2 }\ { c }^{ 2 }={ (12) }^{ 2 }+{ (18) }^{ 2 }\ { c }^{ 2 }=144+324\ { c }^{ 2 }=468\ c=\sqrt { 468 } \ c=21.63$

A triangle whose lengths of sides are $5$ cm, $12$ cm and $13$ cm. The triangle is ____________.

  1. Obtuse-angled triangle

  2. Acute-angled triangle

  3. Right-angled triangle

  4. Triangle is not formed


Correct Option: C
Explanation:
Given sides of triangle are $5$ cm, $12$ cm, $13$ cm
Now applying pythagorus theorem:
$h^{2}= b^{2}+P^{2}$
$\Rightarrow 13^{2}= 12^{2}+5^{2}$
$ \Rightarrow 169 =144+25$
$ \Rightarrow 169 =169$
These three sides clearly satisfy ptyhagorous theorem.
Therefore, the triangle is RIGHT ANGLED triangle.

In any triangle $ABC$,  $AB^{2} + AC^{2} = 3 (AO^{2} + OC^{2})$.
where $O$ is mid-point of $BC$.

  1. True

  2. False


Correct Option: B

Two cars are travelling along two roads which cross each other at right angles at $A$. One car is travelling towards A at $21\ kmph $ and the other is travelling towards $A$ at $28\ kmph$.If initially, their distance from $A$ are $1500\ km$ and $2100\ km$ respectively,then the nearest distance between them is ,

  1. $30$

  2. $45$

  3. $60$

  4. $75$


Correct Option: C
Explanation:
Nearest distance
$=\dfrac{2100-1500}{10}$
$\dfrac{600}{10}=60$







The perpendicular from A on side BC of a $\Delta ABC$ intersects BC at D such that $DB = 3CD$, then $2A{B^2} = A{C^2} + B{C^2}$.

  1. True

  2. False


Correct Option: B

State true or false
In a triangle ABC, P and Q are the id-points of AC and AB respectively and angle $BAC=90^o$.
then $BP^2 + CQ^2=5PQ^2$

  1. True

  2. False


Correct Option: A
Explanation:

In $\triangle BAP$,
$BP^2 = AB^2+ AP^2$ (Pythagoras Theorem)

Since, Q is the mid-point of AB, then $AB = 2 AQ$
Hence, $BP^2 = (2 AQ)^2 + AP^2$
$BP^2 = 4 AQ^2 + AP^2$...(I)

In $triangle QAC$,
$QC^2 = AQ^2 + AC^2$ (Pythagoras theorem)
Since, P is the mid point of AC, $AC = 2 AP$
Hence, $QC^2 = AQ^2 + (2 AP)^2$ 
$QC^2 = AQ^2 + 4 AP^2$...(II)

By Adding I and II
$BP^2 + QC^2 = 4 AQ^2 + AP^2 + AQ^2 + 4 AP^2$
$BP^2 + QC^2 = 5 (AP^2 +AQ^2)$

In $\triangle QAP$,
$AQ^2 + AP^2 = PQ^2$
Hence, $BP^2 + QC^2 = 5 PQ^2$

In a quadrilateral ABCD, $\angle B\, =\, 90^{\circ}$ and $\angle D\, =\, 90^{o}$. Then:

  1. $2{AC}^{2}\, -\, {AB}^{2}\, =\, {BC}^{2}\, +\, {CD}^{2}\, +\, {DA}^{2}$

  2. $2{AC}^{2}\, =\, {BC}^{2}\, +\, {CD}^{2}\, +\, {DA}^{2}$

  3. $2{AC}^{2}\, -\, 2 {AB}^{2}\, =\, {BC}^{2}\, +\, {CD}^{2}\, +\, {DA}^{2}$

  4. $2{AC}^{2}\, =\, 2{BC}^{2}\, +\, {CD}^{2}\, +\, {DA}^{2} + {BC}^2 $


Correct Option: A
Explanation:

In quadrilateral $ABCD$, 

$\angle B = \angle D = 90^{\circ}$
Now, join $AC$
In $\triangle ABC$,
${AC}^2 = {AB}^2 + {BC}^2$
In $\triangle ADC$,
${AC}^2 = {AD}^2 + {CD}^2$
Add both the equations:
$2{AC}^2 = {AB}^2 + {BC}^2 + {AD}^2 + {CD}^2$
Hence, option A.

A grassy land in the shape of a right angled triangle has its hypotenuse $1$ metre more than twice the shortest side. If the third side is $7$ metres more than the shortest side. The sides of the grassy land are:

  1. $8$m, $17$m, $15$m

  2. $2$m, $16$m, $13$m

  3. $10$m, $4$m, $5$m

  4. $7$m, $10$m, $14$m


Correct Option: A
Explanation:

Let the length of the shortest side be $x$ meters. Then,
Hypotenuse = $(2x +1)$ meters, Third side = $(x + 7)$ meters
(Hyppotenuse)$^2$ = sum of the square of the remaining two sides    ....[By pythagorous theroem]
$\Rightarrow (2x + 1)^2 = x^2 + (x + 7)^2$
$\Rightarrow 4x^2 + 4x + 1 = 2x^2 + 14x + 49$
$\Rightarrow 2x^2 - 10x - 48 = 0$
$\Rightarrow x^2 - 5x - 24 = 0$
$\Rightarrow x^2 - 8x + 3x - 24 = 0$
$\Rightarrow x(x - 8) + 3 (x - 8) = 0$
$\Rightarrow (x - 8) (x + 3) = 0$
$\Rightarrow x = 8, -3$
$\Rightarrow x = 8$             [$\because x = -3$ is not possible]
Hence, the lengths of the sides of the grassy land are $8$ m., $17$ m. and $15$ m.

The hypotenuse of a right angled triangle is $25$cm. The other two sides are such that one is $5$cm longer than the other. Their lengths (in cm) are:

  1. $10, 15$

  2. $20, 25$

  3. $15, 20$

  4. $25, 30$


Correct Option: C
Explanation:

Given: Hypotenuse of right triangle $= 25$ cm
Let the other sides be $x$ and $x + 5$
Thus, By Pythagoras Theorem:
$25^2 = x^2 + (x + 5)^2$
$625 = x^2 + x^2 + 25 + 10x$
$2x^2 + 10x - 600 = 0 $
$x^2 + 5x - 300 = 0 $
$x^2 + 20x - 15x - 300 = 0$
$(x + 20) (x - 15) = 0 $
$x = 15, -20$
Thus, the other two sides are $15$ cm and $20$ cm.

Hypotenuse of a right triangle is $25cm$ and out of the remaining two sides, one is longer than the other by $5cm$. Find the lengths of the other two sides.

  1. $10$cm and $20$ cm

  2. $15$cm and $20$ cm

  3. $25$cm and $20$ cm

  4. $5$cm and $20$ cm


Correct Option: B
Explanation:

Let one side be $xcm$. Then the other side will be $(x+5)cm$. Therefore, from Pythagoras theorem
${x}^{2}+{(x+5)}^{2}={25}^{2}$
$\Rightarrow { x }^{ 2 }+{ x }^{ 2 }+10x+25=625$
$\Rightarrow { x }^{ 2 }+5x-300=0\quad \quad \Rightarrow { x }^{ 2 }+20x-15x-300=0$
$\Rightarrow x(x+20)-15(x+20)=0$
$\Rightarrow (x-15)(x+20)=0\quad \Rightarrow \quad x=15\quad or\quad x=-20$
Rejecting $x=-20$, we have length of one side $=15cm$ and that of the other side $=(15+5)cm=20cm$

The lengths of the sides of a right-angled triangle are all given in natural numbers. If two of these numbers are odd and they differ by $50$, then the least possible value for the third side is:

  1. $61$

  2. $60$

  3. $51$

  4. $50$


Correct Option: B
Explanation:

We can observe,considering general numbers for right angled triangle,
$5^2 = 3^2 + 4^2$ (5, 3 are odd and 4 lies between 5, 3)
and  $13^2 = 5^2 + 12^2$ (5, 13 are odd and 12 lies between 5, 13)
By trial and error
$61^2 = 60^2 + 11^2$
Since (61, 11 are odd and 61 hypotenuse)
$61 -11 = 50$
Hence, option 'B' is correct.

The distance between the top of two trees $20$m and $28$m high is $17$m. The horizontal distance between the trees is:

  1. $11$m

  2. $31$m

  3. $15$m

  4. $9$m


Correct Option: C
Explanation:

Consider the two trees as perpendiculars on the ground forming a right triangle, where the distance between their bases is the base $(B)$, the distance between their tops is the Hypotenuse $(H)$ and difference between their lengths is the perpendicular $(P)$.
Hypotenuse, $H = 17$ m
Perpendicular, $P=$ distance between their lengths $= 28 - 20 = 8$ m
Thus, By Pythagoras Theorem,
$H^2 = P^2 + B^2$
$17^2 = 8^2 + B^2$
$B^2 = 289 - 64$
$B = 15m$.

One side other than the hypotenuse of a right-angled isosceles triangle is $4$ cm. The length of the perpendicular on the hypotenuse from the opposite vertex is:

  1. $8$cm

  2. $4\sqrt { 2 } $cm

  3. $4$ cm

  4. $2\sqrt { 2 } $cm


Correct Option: D
Explanation:
Let assume A, B, C be the vertices of the given triangle and right-angled at A i.e, $\angle A = 90^{\circ}$, $AD \perp BC$.......(D is the point of intersecton of perpendicular from A on BC)
By Pythagoras theorem,
$BC^2 = AB^2 + AC^2$
$BC^2 = 4^2 + 4^2$
$BC = 4\sqrt{2}$ cm
Area of triangle = $\frac{1}{2} base \times height$
Thus, $\frac{1}{2} AB \times AC = \frac{1}{2} AD \times BC$
$4 \times 4 = 4\sqrt{2} \times AD$
$AD = 2 \sqrt{2}$ cm

The length of the hypotenuse of a right angled $\Delta$ whose two legs measure $12 \ cm$ and $0.35 \ m$ is:

  1. $37 \ cm$

  2. $3.72 \ cm$

  3. $0.372 \ cm$

  4. $37 \ m$


Correct Option: A
Explanation:

$0.35 \ m = 0.35 \times 100 \ cm = 35 \ cm.$
We have,
$(hypotenuse)^2\, =\, (side)^2\, +\, (side)^2$
$=\, (12)^2\, +\, (35)^2$
$= 144 + 1225$
$= 1369$
Hypotenuse $=\sqrt{1369} = 37 \ cm.$

In a $\Delta ABC,\,AB=AC=2.5\;cm,\,BC=4\;cm$. Find its height from $A$ to the opposite base.

  1. $1.5\;cm$

  2. $1\;cm$

  3. $2\;cm$

  4. $3\;cm$


Correct Option: A
Explanation:

$In\triangle ABC $


In order to find height we need to consider that $  AD\bot BC$

$ Hence\quad in\quad right\quad angled \ \triangle ADC$

$ { AC }^{ 2 }={ AD }^{ 2 }+{ DC }^{ 2 }(Phythagoreas\quad Theorm)$

$ \Rightarrow { AD }^{ 2 }={ AC }^{ 2 }-{ DC }^{ 2 }$

$ \Rightarrow { AD }^{ 2 }={ (2.5) }^{ 2 }-({ 2) }^{ 2 }$

$ \Rightarrow { AD }^{ 2 }=6.25-4$

$ \Rightarrow { AD }^{ 2 }=2.25$

$ \Rightarrow AD=1.5$

$ Hence\quad option\quad (A)\quad is\quad right\quad answer$

If the sum of the length, breadth and depth of a cuboid is S and its diagonal is d, then its surface is _____________.

  1. $S^2$

  2. $d^2$

  3. $S^2-d^2$

  4. $S^2+d^2$


Correct Option: C

In $\Delta$ABC, $\angle B = 90^{o}, AB = 8 \ cm$ and $BC = 6 \ cm.$ The length of the median $BM$ is:

  1. $3 \ cm$

  2. $5 \ cm$

  3. $4 \ cm$

  4. $7 \ cm$


Correct Option: B
Explanation:
$AC^2= AB^2+ BC^2$        (because $\angle B = 90^o$)
$= 64+36= 100$
$\therefore AC = 10$
In a right triangle, the median from the right angle to the hypotenuse is half the length of the hypotenuse. 
So, $\displaystyle BM = \frac{1}{2} AC = \frac{10}{2} = 5 \ cm.$

If the sides of a right angled triangle are $x, 3x + 3$  and $3x + 4$, then $x$ is equal to:

  1. $-1$

  2. $7$

  3. $6$

  4. Both A and B


Correct Option: B
Explanation:

As the sides are of a right angled triangle, we have
$ {Hypotenuse}^{2} = {Side1}^{2} + {Side2}^{2} $ where hypotenuse is the largest side.
$ {(3x+4)}^{2}  = {(3x+3)}^{2} + {x}^{2} $
$ => 9{x}^{2} + 16 + 24x = 9{x}^{2} + 9 + 18x + {x}^{2}  $
$ => {x}^{2} - 6x - 7 = 0 $
$ => {x}^{2} - 7x + x - 7 = 0 $
$ => x(x-7) + (x-7) = 0 $
$ => (x-7)(x+1) = 0 $
$ => x = 7, -1 $
As the side cannot be negative, $ x = 7 $.

In a field of shape of a right angled triangle, the farmer wants to measure the $3$ sides but being a huge field, he was only able to measure $2$ sides, $1$ side of which was $6$ km and other was $8$ km. Can you find the length of $3^{rd}$ side for him?

  1. $10$ km

  2. $8$ km

  3. $14$ km

  4. $13$ km


Correct Option: A
Explanation:

The field is in the shape of a right angled triangle.

Using Pythagoras theorem,
$6^2 + 8^2 = \mbox{(3rd side)}^2$
$\mbox{(3rd side)}^2 = 36 + 64$
$\mbox{(3rd side)}^2 = 100$
$\therefore \mbox{3rd side} = 10$ km
So, option A is correct.

If the Pythagorean triples of one member is $10$, find the other two members.

  1. $24$ and $25$

  2. $24$ and $26$

  3. $22$ and $25$

  4. $23$ and $25$


Correct Option: B
Explanation:

As we know $2m,$ $m^{2}+1, m^{2}-1$ form a Pythagorean triplet for any number $m > 1$.
Let us assume $2m = 10$
$\Rightarrow m = 5$
Therefore, $m^{2}+1$ $=$ $5^{2}+1$
$\Rightarrow 25 + 1 = 26$
$m^{2}-1$ = $5^{2}-1$
and $\Rightarrow 25 - 1 = 24$
Hence, the other two members are $24$ and $26$.

If the Pythagorean triples of one member is $8$, find the other two members.

  1. $15$ and $17$

  2. $14$ and $17$

  3. $15$ and $16$

  4. $11$ and $17$


Correct Option: A
Explanation:

As we know $2m,$ $m^{2}+1, m^{2}-1$ form a Pythagorean triplet for any number $m > 1$.
Let us assume $2m = 8$
$\Rightarrow m = 4$
Therefore, $m^{2}+1$ $=$ $4^{2}+1$
$\Rightarrow 16 + 1 = 17$
and $m^{2}-1$ $=$ $4^{2}-1$
$\Rightarrow 16 - 1 = 15$
Hence, the other two members are $15$ and $17$.

If the Pythagorean triples of one member is $22$, find the other two members.

  1. $124$ and $122$

  2. $123$ and $122$

  3. $121$ and $122$

  4. $120$ and $122$


Correct Option: D
Explanation:

As we know $2m$, $m^{2}+1, m^{2}-1$ form a Pythagorean triplet for any number $m > 1$.


Let us assume $2m = 22$

$\Rightarrow m = 11$

Therefore, $m^{2}+1$ $=$ $11^{2}+1$

$\Rightarrow 121 + 1 = 122$

and $m^{2}-1$ $=$ $11^{2}-1$

$\Rightarrow 121 - 1 = 120$

Hence, the other two members are $120$ and $122$.

Which of the following can't be  the lengths of the sides of a right-angled triangle?

  1. $5$ inches, $12$ inches, $13$ inches

  2. $\displaystyle\frac{1}{3}$ of a foot, $\displaystyle\frac{1}{4}$ of a foot, $\displaystyle\frac{1}{5}$ of a foot

  3. $9$cm, $40$cm, $41$cm

  4. $\displaystyle\frac{3}{4}$ of a foot, $1$ foot, $15$ inches


Correct Option: B
Explanation:

For a set of numbers to be sides of a right angled triangle, the square of the longest side must equal the sum of the squares of the other two sides.

In option A, $13^2 = 169, 5^2 + 12^2 = 169$ so possible.
In option B, $\left (\dfrac{1}{3}\right)^2 = \dfrac{1}{9}, \left (\dfrac{1}{4}\right)^2 + \left (\dfrac{1}{5}\right)^2 = \dfrac{41}{400}$
Since, these two values are not equal, this set cannot form a right angled triangle.

The ratio of the two legs of a right-angled triangle is $3:1$. If the lengths of the legs are whole numbers, what can be the possible value of the hypotenuse?

  1. $\sqrt{40}$

  2. $\sqrt{47}$

  3. $\sqrt{55}$

  4. $\sqrt{63}$


Correct Option: A
Explanation:

The legs of a right angled triangle are in the ratio $3:1$ and they are whole numbers.

The possibilities are as listed below:
$3,1$ - The hypotenuse becomes $\sqrt{(3)^2 + (1)^2} = \sqrt{10}$
$6,2$ - The hypotenuse becomes $\sqrt{(6)^2 + (2)^2} = \sqrt{40}$
$9,3$ - The hypotenuse becomes $\sqrt{(9)^2 + (3)^2} = \sqrt{90}$
Thus, the hypotenuse will always be square root of a multiple of $10$, which is in option A.

A man goes $12$ miles due east and then $9$ miles due north. Calculate the distance travelled, if he takes the theoretically shortest path.

  1. $3$

  2. $\sqrt {63}$

  3. $15$

  4. $21$

  5. $225$


Correct Option: C
Explanation:

It will form a right angled triangle where one side is $12$ miles and the other sides is $9$ miles. 

Now we know that the sum of two sides is greater the the third side. 
Hence he travels $21$ miles, but if he takes the shortest path then he will walk along the hypotenuse. 
The length of the hypotenuse will be 
$=\sqrt{12^{2}+9^{2}}=\sqrt{144+81}=\sqrt{225}=15$

A boat travels $10$ miles East and then $24$ miles South to an island. How many miles are there from the point of departure of the boat to the island?

  1. $34$

  2. $14$

  3. $26$

  4. $2\sqrt{119}$

  5. $44$


Correct Option: C
Explanation:

While travelling to $10$ miles East and then $24$ miles South the boat is moving on the path to form a right angled triangle.
The distance $c$ then would be the hypotenuses of the triangle, which can be calculated using Pythagorean Theorem which is ${ a }^{ 2 }{ +b }^{ 2 }={ c }^{ 2 }$.    
As we have the measurements of the two sides making the right angle: 
$\Rightarrow { 10 }^{ 2 }{ +24 }^{ 2 }={ c }^{ 2 }$
$\Rightarrow 100 + 576 =$ ${ c }^{ 2 }$
$\Rightarrow { c }^{ 2 }$ $= 676$
$\Rightarrow { c }$ $= 26$ miles
Hence, the option C is the right answer.
Ans: C

Sheila leaves her house and starts driving due south for $30$ miles, then drives due west for $60$ miles, and finally drives due north for $10$ miles to reach her office. Find her approximate displacement.

  1. $63$

  2. $67$

  3. $71$

  4. $75$

  5. $80$


Correct Option: A
Explanation:

The resultant distance she traveled towards south is equal to $30-10 = 20$ miles

The resultant distance she traveled towards west is $60$ miles
The displacement is $\sqrt { { 60 }^{ 2 }+{ 20 }^{ 2 } } =\sqrt { 3600+400 } =\sqrt { 4000 } =63$ (approx)

$\angle B$ in $\triangle ABC$ and $\angle S$ in $\triangle RST$ are right angles. The lengths of sides $AC$ and $RT$ are equal. Determine the relation between the following.

A: The length of side $AB$.
B: The length of side $RS$.

  1. The quantity in statement A is greater than B.

  2. The quantity in statement B is greater than A.

  3. The two quantities are equal.

  4. The relationship cannot be determined from the given information.


Correct Option: D
Explanation:

In $\triangle ABC$ and $\triangle RST$,

hypt. $AC=$ hypt. $RT$

$\therefore AC^2 = RT^2$

$\therefore { AB }^{ 2 }+{ BC }^{ 2 }={ RS }^{ 2 }+{ ST }^{ 2 }$.

which does not imply that $AB=RS$.
So, the relationship cannot be determined.

The sides of a triangle are $25 m$, $39 m$ and $56 m$ respectively. Find the length of perpendicular from the opposite angle on the greatest sides.

  1. $56 m$

  2. $60 m$

  3. $15 m$

  4. $12 m$


Correct Option: C
Explanation:

Let $a=25 \ m, \ b=39 \ m, \ c=56 \ m$


We have, semi-perimeter, $s=\dfrac{a+b+c}{2}$

$s=\dfrac{25+39+56}{2}$

$s=\dfrac{120}{2}=60 \ m$

$Area \ of \ triangle = \sqrt{s(s-a)(s-b)(s-c)}$

$=\sqrt{60(60-25)(60-39)(60-56)}$

$=\sqrt{60(35)(21)(4)}=\sqrt{176400}$

$=420 \ m^2$


$Area \ of \ triangle = \dfrac{1}{2}bh$,    where b-base and h-height

$base=greatest side=56 \ m$

$420=\dfrac{1}{2}(56)h$

$h=\dfrac{840}{56}$

$h=15 \ m$

In $\triangle ABC,\angle ABC={ 90 }^{ o }$. If $AC=(x+y)$ and $BC=(x-y)$, then the length of $AB$ is:

  1. ${ x }^{ 2 }-{ y }^{ 2 }$

  2. $2xy$

  3. $2\sqrt { xy } $

  4. ${ x }^{ 2 }+{ y }^{ 2 }$


Correct Option: C
Explanation:

Given, $\angle ABC=90^{\circ},$

Also, $AC=(x+y)$ and $BC=(x-y)$
We need to find the length of $AB$.
Now as $\angle ABC=90^{\circ},$ at $B$ we can use Pythagoras theorem
$\therefore$  $AB^2+BC^2=AC^2$
$\implies$  $AB^2=AC^2-BC^2$
$\implies$  $AB^2=(x+y)^2-(x-y)^2$
Using the formula for $(a+b)^2$ and $(a-b)^2$
$\implies$ $AB^2=x^2+2xy+y^2-(x^2-2xy+y^2)$
By cancelling the like terms we get,
$AB^2=4xy$
Taking square root on both the sides we get,
$AB=2\sqrt{xy}$.
Hence, the answer is C,

A pilgrim started from a shrine. After walking straight for $100 m$, he moved to his right and then after $500 m$, he again moved to his right. After walking a distance of $100 m$, he moved to his left and then walked $200 m$. He again moved to his right and walked $700 m$. 
What is the distance of his location from the shrine?

  1. $990\ m$

  2. $1300\ m$

  3. $1400\ m$

  4. $2100\ m$


Correct Option: A
Explanation:

Suppose a pilgrim starts from point $A$.

As per the given data, suppose he stops at point $C$.
So, at the end he makes a right angle triangle $ABC$, with $\angle B=90^{o}$.
Base $BC=700m$ and height $AB=700m$.
Then by Pythagoras theorem,
$AC^2=AB^2+BC^2$
         $=700^2+700^2$
         $=4900+4900=9800$
$\therefore \ AC=990m$.

$PQ$ is the diameter of a semicircle with radius $4\ cm$ and $\angle PRQ$ is the angle on the semicircle. If $QR = 2\sqrt {7} cm$, then length of $PR$ is :

  1. $8\ cm$

  2. $6\ cm$

  3. $5\ cm$

  4. $2\sqrt {11} cm$


Correct Option: B
Explanation:

$\angle PRQ = 90^{\circ}\Rightarrow PR = \sqrt {(PQ)^{2} - (RQ)^{2}}$

                                       $= \sqrt {64 - 28} $

                                       $= 6$.
$\therefore$ The solution is $6$

In a triangle $ABC$ with $\angle A = 90^o$, $P$ is a point on $BC$ such that $PA : PB = 3:4$. If $AB=\sqrt{7}$ and $AC=\sqrt{5}$, then $BP:PC$ is 

  1. $2:1$

  2. $4:3$

  3. $4:5$

  4. $8:7$


Correct Option: A

Triangle $ABC$ is right angled at $A$. The points $P$ and $Q$ are on the hypotenuse $BC$ such that $BP = PQ = QC$.
If $AP = 3$ and $AQ = 4$, then the length $BC$ is equal to

  1. $\sqrt { 27 } $

  2. $\sqrt { 36 } $

  3. $\sqrt { 45 } $

  4. $\sqrt { 54 } $


Correct Option: C
Explanation:

$BP=PQ=QC=x(let)$

$ AP=3;AQ=4$
$ In\triangle AQB$
$ AP\quad is\quad median\quad by\quad Apollonius\quad Thm$
$ { AB }^{ 2 }+{ AQ }^{ 2 }=2({ AP }^{ 2 }+{ PQ }^{ 2 })$
$\implies\quad { AB }^{ 2 }+16=2(9+{ x }^{ 2 })$
$\implies\quad { AB }^{ 2 }=2{ x }^{ 2 }+2\quad -(1)$
$ Similarly,in\triangle APC$
$ AQ\quad is\quad median$
$ So,$
$ { AC }^{ 2 }+{ AP }^{ 2 }=2({ AQ }^{ 2 }+{ QC }^{ 2 })$
$ \therefore { AC }^{ 2 }+9=2(16+{ x }^{ 2 })$
$\implies\quad { AC }^{ 2 }=2{ x }^{ 2 }+23\quad -(2)$
$ (1)+(2)$
$ { AB }^{ 2 }+{ AC }^{ 2 }=4{ x }^{ 2 }+25$
$\implies\quad { BC }^{ 2 }=4{ x }^{ 2 }+25\quad [In\triangle ABC,using\quad pythagoras\quad thm]$
$\implies\quad { (3x) }^{ 2 }=4{ x }^{ 2 }+25$
$\implies\quad 9{ x }^{ 2 }=4{ x }^{ 2 }+25$
$\implies\quad x=\sqrt { 5 } $
BC=3x=$\sqrt { 45 } $

Given that in a right angled triangle the length of two sides are 11 and 60. Find the perimeter of the triangle.

  1. $132$

  2. $145$

  3. $89$

  4. $200$


Correct Option: A
Explanation:
$\begin{array}{l} { 11^{ 2 } }+{ 60^{ 2 } }={ 61^{ 2 } } \\ \Rightarrow Perimeter\, \, of\, \, \Delta =132\, \, cm \\ \left\{ { \because sides\, \, 11,60\, \, \& \, \, 61 } \right\}  \end{array}$

In a right angled triangle the hypotenuse is  $2\sqrt{2}$ times the length of the perpendicular drawn from the opposite vertex on the hypotenuse. The the other two angles are

  1. $\left( \dfrac { \pi }{ 3 } ,\dfrac { \pi }{ 6 } \right)$

  2. $\left( \dfrac { \pi }{ 4 } ,\dfrac { \pi }{ 4 } \right)$

  3. $\left( \dfrac { \pi }{ 8} ,\dfrac { 3\pi }{ 8 } \right)$

  4. $\left( \dfrac { \pi }{ 12 } ,\dfrac { 5\pi }{ 12 } \right)$


Correct Option: C

In a right angled triangle, the square of the hypotenuse is equal to twice the product of the other two sides. One of the acute angles of the triangle is:

  1. $40^0$

  2. $42^0$

  3. $44^0$

  4. $45^0$


Correct Option: D
Explanation:

Let $\triangle ABC$ be right angled at B.

Then, by Pythagoras theorem,

$AC^2 = AB^2+BC^2$

But $AC^2 = 2 \times AB . BC$     .....Given

Hence, $AB^2 + BC^2 = 2 \times AB. BC$

$AB^2 + BC^2 - 2 \times AB. BC = 0$

$(AB - BC)^2 = 0$

So, $AB = BC$

Therefore, $\triangle ABC$ is right isosceles triangle.

So, $\angle A = \angle C = 45^o$.

Evaluate cos$\begin{pmatrix}2csc^{-1}(\dfrac{x+4}{5})\end{pmatrix} = $

  1. $\dfrac{x^2+8x-16}{x+4}$

  2. $\dfrac{x^2+8x-16}{(x+4)^2}$

  3. $\dfrac{x^2+8x-34}{x+4}$

  4. $\dfrac{x^2+8x-34}{(x+4)^2}$

  5. $\dfrac{-16-8x-x^2}{(x+4)^2}$


Correct Option: D
Explanation:

Let $\theta =\csc ^{ -1 }{ \left( \dfrac { x+4 }{ 5 }  \right)  }$ implies that $\csc { (\theta )=\dfrac { x+4 }{ 5 }  }$ and therefore, $\sin { (\theta ) } =\dfrac { 5 }{ x+4 }$.


Use the pythagorean theorem to determine that the remaining leg of the right triangle has length:

$\sqrt { (x+4)^{ 2 }-5^{ 2 } } =\sqrt { x^{ 2 }+16+8x-25 } =\sqrt { x^{ 2 }+8x-9 }$

Therefore, $\cos { (\theta ) } =\dfrac { \sqrt { x^{ 2 }+8x-9 }  }{ x+4 }$  

Hence, $\cos { (2\theta ) } =\cos ^{ 2 }{ (\theta ) } -\sin ^{ 2 }{ (\theta ) } $
$=\left( \dfrac { \sqrt { x^{ 2 }+8x-9 }  }{ x+4 }  \right) ^{ 2 }-\left( \dfrac { 5 }{ x+4 }  \right) ^{ 2 }$
$=\dfrac { x^{ 2 }+8x-9 }{ \left( x+4 \right) ^{ 2 } } -\dfrac { 25 }{ \left( x+4 \right) ^{ 2 } } $
$=\dfrac { x^{ 2 }+8x-34 }{ \left( x+4 \right) ^{ 2 } }$ 

Diagonals $\overline{AC}$ and $\overline{BD}$ of quadrilateral $ABCD$ are perpendicular. $AD=DC=8, AC=BC=6, m\angle ADC = 60^o$. The area of $ABCD$ is

  1. $4\sqrt{5}+8\sqrt{3}$

  2. $16\sqrt{3}$

  3. $32\sqrt{3}$

  4. $8\sqrt{5}+16\sqrt{3}$

  5. $48$


Correct Option: D
Explanation:

The altitude to the base of an isosceles triangle also bisects the vertex angle, so $m\angle ADE=30$.

With the hypotenuse of the triangle having a length of $8$, $AE=4$ and $DE=4\sqrt { 3 }$.
$\triangle AEC$ is a right angle with leg $4$ and hypotenuse $6$.
Use the pythagorean theorem to determine that 
$BE=\sqrt { 6^{ 2 }-4^{ 2 } } =\sqrt { 36-16 } =\sqrt { 20 } =2\sqrt { 5 }$
The area of the quadrilateral with perpendicular diagonals is equal to half the product of the diagonals, so the area of $ABCD$ is:
$A=\dfrac { 1 }{ 2 } \times 8\times (2\sqrt { 5 } +4\sqrt { 3 } )=4(2\sqrt { 5 } +4\sqrt { 3 } )=8\sqrt { 5 } +16\sqrt { 3 }$  

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