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Parallelogram and rectangle - class-IX

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If the area of a parallelogram is $144 \operatorname { cm } ^ { 2 }$ and its base is $9 cm$. then its height is 

  1. $8 cm$

  2. $12 cm$

  3. $24 cm$

  4. $16 cm$


Correct Option: D
Explanation:

Area of parallelogram $=base\times height$


$\Rightarrow$ $144{cm}^{2}=9cm\times 10cm$


$\Rightarrow$ $h$ in $cm=\cfrac{144{cm}^{2}}{9cm}$

$\therefore$ $h=16cm$

Hence height $=16cm$

Area of the parallelogram formed by the pairs of lines $x^{2}+xy-^{2}=0$ and $x^{2}+xy-y^{2}-3x-4y+1=0$ is

  1. $\sqrt {5}$

  2. $\dfrac {1}{\sqrt {5}}$

  3. $2\sqrt {5}$

  4. $\dfrac {2}{\sqrt {5}}$


Correct Option: C

A parallelogram has sides 12 cm and 9 cm. If the distance between its shorter sides is 8 cm, find the distance between its longer side.

  1. $3 \ cm$

  2. $6 \ cm$

  3. $9 \ cm$

  4. $12 \ cm$


Correct Option: B
Explanation:

Adjacent sides of parallelogram $= 12\ cm$ and $9\ cm$

Distance between shorter sides $= 8\ cm$

Area of parallelogram = $b \times h =9 \times 8 =72 \ cm^2$

Again, area of parallelogram = $b \times h$
$72 =12 \times h$
$h= 6 \ cm$

Therefore, the distance between its longer side $= 6\ cm.$

The area of parallelogram if the base is $36cm$  and height is $45cm$

  1. 1620

  2. 1800

  3. 1250

  4. 1640


Correct Option: A
Explanation:

The base of parallelogram is $36cm$

The height is $45cm$
The area of parallelogram is $36\times 45=1620cm^2$

If $ABCD$ is a parallelogram then the ratio of the areas of parallelogram $ABCD$ and $\displaystyle \Delta ABC$ is

  1. $1 : 2$

  2. $2 : 1$

  3. Cannot be determined

  4. None


Correct Option: B
Explanation:

$2 : 1$
Diagonal resolves a parallelogram into two equal triangles.

Find the area of the parallelogram whose base is $17\ cm$ and height $0.8\ m$?

  1. $\displaystyle 13.6:cm^{2}$

  2. $\displaystyle 1360:cm^{2}$

  3. $\displaystyle 13.6:m^{2}$

  4. $\displaystyle 1360:m^{2}$


Correct Option: B
Explanation:

Base $= 17\ cm$
Height $= 0.8\ m =0.8 \times 100 = 80\ cm$
Area of parallelogram 
$= b \times h$
$= 17\times 80$
$= 1360\ cm^2$

A rectangle and a parallelogram have equal areas. If the sides of the rectangle are $10 m$ and $12 m$ and the base of the parallelogram is $20 m$, then the altitude of the parallelogram is:

  1. $7 m$

  2. $6 m$

  3. $5 m$

  4. $3 m$


Correct Option: B
Explanation:

Area of the rectangle $= l \times b = 10 m \times 12 m$
                                     $= 120 m^{2}$
Area of parallelogram $= Base \times Altitude= 120 m^{2}$
$ \Rightarrow$ Altitude $= \cfrac{Area }{Base}=\cfrac{120m^{2}}{20m}=6m$

A rectangle and a parallelogram have equal areas. The base of the parallelogram is $20 cm$ and the altitude is $6 cm$. Which one of the following cannot be the ratio of dimensions of the rectangle?

  1. $7 : 5$

  2. $40 : 3$

  3. $15 : 2$

  4. $30 : 1$


Correct Option: A
Explanation:

Area of the rectangle $=$ Area of parallelogram
                                     $= 20 cm \times 6 m = 120 \displaystyle cm^{2}$
Now,                 
Ratio $= 7 : 5$             Ratio $= 40 : 3$
Product $= 35$            Product $= 120$
-------------------------------------------------------------
Ratio $= 15 :2$           Ratio $= 30 : 1$
Product $= 30$            Product $= 30$
$\displaystyle \therefore $ Ratio $= 7 : 5$ does not match with the condition as $120$ is not divisible by $35$.

The area of a parallelogram is $120$  $cm^{2}$ and its altitude is $10$ cm. The length of the base is

  1. $24$ cm

  2. $12$ cm

  3. $8$ cm

  4. $4$ cm


Correct Option: B
Explanation:

Area of parallelogram 
= $Base \times height = 120 cm^{2}$.
$\therefore $  Base = $12 cm$

One side of a parallelogram is 8 cm. If the corresponding altitude is 6 cm, then its area is given by

  1. 24 $cm^2$

  2. 36 $cm^2$

  3. 40 $cm^2$

  4. 48 $cm^2$


Correct Option: D
Explanation:

As we know,

Area of Parallelogram $=bh$
Here, $b=8$ cm, $h=6$ cm
Area of Parallelogram $=8\times 6$
Area of Parallelogram $=48\ cm^2$.

One side of a parallelogram is 8 cm If the corresponding altitude is 6 cm then its area is given by

  1. 24 $ \displaystyle cm ^{2} $

  2. 36 $ \displaystyle cm ^{2} $

  3. 40 $ \displaystyle cm ^{2} $

  4. 48 $ \displaystyle cm ^{2} $


Correct Option: D
Explanation:

Given One side of parallelogram is 8 cm and altitude is 6 cm 

Here base=8 cm and height(altitude)=6 cm
We know that area of parallelogram=$base \times hieght$

Here base=8 cm and height(altitude)=6 cm
Then area of  parallelogram=$8\times 6=48 cm^{2}$

The height of a parallelogram of area $ \displaystyle   350 cm^{2}   $ and base 25 cm is

  1. 12 cm

  2. 13 cm

  3. 14 cm

  4. 15 cm


Correct Option: C
Explanation:

Given the area of parallelogram is 350 sq cm and base is 25 cm

Then area of  parallelogram if height h and base 25
$\therefore 350=base \times height\Rightarrow 25\times h=350\Rightarrow h=14$ cm

Two adjacent sides of a parallelogram are x and y and the included angle is $\displaystyle \alpha  $ then the area of the parallelogram is

  1. xy $\displaystyle \cot \alpha $

  2. xy $\displaystyle \cos \alpha $

  3. xy $\displaystyle \sin \alpha $

  4. none of these


Correct Option: C
Explanation:

Given the two adjacent sides of a parallelogram is x and y and angle is $\alpha $

let the height of  parallelogram is h
Then $sin \alpha=\frac{h}{y}\Rightarrow h=y sin \alpha  $

So area of   parallelogram=$base\times heigth=x\times ysin\alpha =xy sin\alpha $

What will be area of a parallelogram with base 6 cm and altitude 3.5 cm---

  1. 28 square cm

  2. 20 square cm

  3. 21 square cm

  4. None of these


Correct Option: C
Explanation:

Area = Base $\times$ Altitude
         = 6 cm $\times$ 3.5 cm
         = 21 square cm

In a trapezium whose parallel sides measure 12 cm and 10 cm and the distance between them is 8 cm. Find the area of trapezium---

  1. 84 $cm^2$

  2. 48 $cm^2$

  3. 88 $cm^2$

  4. 188 $cm^2$


Correct Option: C
Explanation:

Area of trapezium = $\displaystyle \frac{h}{2} (a + b)$
                                = $\displaystyle \frac{8}{2} (12 + 10)$
                                = 4 $\times$ 22 = 88 $cm^2$

Find the area of the parallelogram whose base is 16 cm and height 0.4 m ?

  1. 440 $cm^2$

  2. 740 $cm^2$

  3. 640 $cm^2$

  4. None of these


Correct Option: C
Explanation:

Base = 16 cm
Height = 0.4 m
            = 0.4 $\times$ 100 = 40 cm
Area of parallelogram = b $\times$ h
                                      = 16 $\times$ 40
                                      = 640 $cm^2$

In a parallelogram the base and height are is in the ratio of $5 : 2$. If the area of the parallelogram is $360\ m^{2}$, find its base and height.

  1. $30\ m, 12\ m$.

  2. $20\ m, 12\ m$.

  3. $30\ m, 10\ m$.

  4. None of these


Correct Option: A

One side of a parallelogram is $8$ cm. If the corresponding altitude is $6$ cm, then its area is given by

  1. $24: cm^2$

  2. $36: cm^2$

  3. $40: cm^2$

  4. $48: cm^2$


Correct Option: D
Explanation:

Area of parallelogram $=$ length $\times$ height
Here altitude is nothing but the height
$\therefore $ Area of parallelogram $= 8 \times 6$
$= 48: cm^2$

If the base and altitude of a parallelogram are doubled, what happens to the area compared to the original one?

  1. $8$ times original

  2. $2$ times original

  3. $4$ times original

  4. Remains same


Correct Option: C
Explanation:

Area of parallelogram $S _1=bh$


New Area, $S _2=2b\times 2h=4bh=4S _1$

$A, B, C, D$ are mid points of sides of parallelogram $PQRS$. If $ar(PQRS)=36\ cm^{2}$ then $ar(ABCD)$

  1. $24\ cm^{2}$

  2. $18\ cm^{2}$

  3. $30\ cm^{2}$

  4. $36\ cm^{2}$


Correct Option: B
Explanation:
$A,B,C,D$ are point of sides of parallelogram $PQRS$ area $(PQRS)=36\ cm^2 ar (ABCD)=?$
$AP=\dfrac {1}{2}SP,\ BP=\dfrac {1}{}QR$
$PS=QR, \dfrac {1}{2}PS=\dfrac {1}{2} QR$
area $(\triangle ABC)=\dfrac {1}{2} (\triangle PQCQ)$
area $(\triangle ADC)=\dfrac {1}{2} ar (ACRS)$
area $\triangle ABC+area (\triangle ADC)=\dfrac {1}{2} area (APCQ)=\dfrac {1}{2}area (ACRS)$
$area (ADCD)=\dfrac {1}{2}area (APCQ)+(ACRS)area $
$area (ABCD)=\dfrac {1}{2} area (PQRS)$
$area (ABCD)=\dfrac {1}{2} (36)$
$=18\ cm^2$


A parallelogram has sides $30m$ and $14m$ and one of its diagonals is $40m$ long. Then, its area is:

  1. $168{m}^{2}$

  2. $336{m}^{2}$

  3. $372{m}^{2}$

  4. $480{m}^{2}$


Correct Option: A
Explanation:
Area of parallalogram = $2\times area of triangle $
Area of triangle where three sides a,b,c are given is $\sqrt{s(s-a)(s-b)(s-c)}$, where $s=\dfrac{a+b+c}{2}$
Here $s=\dfrac{30+14+40}{2}=42$
$Area\ of \triangle=\sqrt{(42)(12)(28)(2)}=\sqrt{28224}=168m^2$
Therefore area of parallalogram = $336 m^2$
Hence option B is correct

The area of the parallelogram with diagonals $5cm, 6cm$ respectivelu

  1. $18cm^2$

  2. $27cm^2$

  3. $15cm^2$

  4. $None\ of\ these$


Correct Option: C
Explanation:

The diagonals of parallelogram is $5cm,6cm$

The area of parallelogram is $\dfrac 12d _1\times d _2\\dfrac 12\times 5\times 6=15cm^2$

Point $A(2,1),B(3,-7),C$ is any point on the line $3x-2y=1$, then locus of point $D$ such that$ABCD$ is a parallelogram

  1. $3x-2y=20$

  2. $3x-y=20$

  3. $2x+3y=20$

  4. $3x-2y+18=0$


Correct Option: A

The area four walls of a hall is $320\ m^{2}$. The length & breadth of the hall is $12.5\ m$ & $7.5\ m$ respectively, Find the height of the hall.

  1. $32\ m$

  2. $9\ m$

  3. $3\ m$

  4. $5\ m$

  5. $None\ of\ these$


Correct Option: A
Explanation:
formula,

$\dfrac{(l+b)h}{2}=area$

$\dfrac{(12.5+7.5)h}{2}=320$

$(12.5+7.5)h=640$

$20h=640$

$\therefore h=32m$

if $\hat { i } +2\hat { j } +3\hat { k } $ and $ 3\hat { i } -2\hat { j } +\hat { k } $ are the adjacent sides of a parallelogram, then its area will be 

  1. $8\sqrt { 3 } $

  2. $5\sqrt { 3 } $

  3. $16\sqrt { 3 } $

  4. $6\sqrt { 3 } $


Correct Option: A
Explanation:

We have,

$ \overrightarrow{a}=\widehat{i}+2\widehat{j}+3\widehat{k} $

$ \overrightarrow{b}=3\widehat{i}-2\widehat{j}+\widehat{k} $


We know that,

Area of parallelogram $=\left| \begin{matrix} i & j & k \\ 1 & 2 & 3 \\ 3 & -2 & 1 \end{matrix} \right| $

$ =\left( -6-2 \right)\widehat{i}-\widehat{j}\left( 9-1 \right)+\widehat{k}\left( 6+2 \right) $

$ =-8\widehat{i}-8\widehat{j}+8\widehat{k} $


$ Now, $

$ \left| \overrightarrow{a}\times \overrightarrow{b} \right|=\sqrt{{{\left( -8 \right)}^{2}}+{{\left( -8 \right)}^{2}}+{{8}^{2}}} $

$ =\sqrt{64+64+64} $

$ =\sqrt{3\times 64} $

$ =8\sqrt{3}\,\,sq.\,unit $


Hence, this is the answer.

ABCD is a parallelogram with sides $AB = 12\ cm$, $BC = 10\ cm$ and diagonal $AC = 16\ cm$. Find the approximate area of the parallelogram.

  1. $119.8cm^2$

  2. $103.7cm^2$

  3. $15.7cm^2$

  4. None of these


Correct Option: A
Explanation:
Area of triangle with sides $12\ cm, 10\ cm, 16\ cm$:
$s=\dfrac{12+10+16}{2}=19$

Area, A = $\sqrt{s(s-a)(s-b)(s-c)}$

$A=\sqrt{19(19-12)(19-10)(19-16)}$

$A=59.9$ sq. cm

Therefore,
Area of parallelogram $=2A = 2\times 59.9 = 119.8$ sq. cm

Which of the following statements are true (T) and which are false (F)?
If three angles of a quadrilateral are equal, it is a parallelogram.

  1. True

  2. False


Correct Option: B

Which of the following statements are true (T) and which are false (F)?
If three sides of a quadrilateral are equal, it is a parallelogram.

  1. True

  2. False


Correct Option: B
Explanation:

$\Rightarrow$  We know that, in parallelogram opposite sides are parallel and equal in length.

$\Rightarrow$  In some case all four sides are equal in length. ( Square and rhombus )
$\Rightarrow$  But we can't say that, three sides are equal than that is a parallelogram. That doesn't satisfied the properties of a parallelogram.
$\therefore$  If three sides of a quadrilateral are equal then it is not a parallelogram.
$\therefore$  The given statement is false.
 

Two opposite angles of a parallelogram are $(3x-2)^{\circ}$ and $(50-x)^{\circ}$. Find the measure of each angle of the parallelogram.

  1. $40^{\circ},140^{\circ},40^{\circ},140^{\circ}$

  2. $37^{\circ},143^{\circ},37^{\circ},143^{\circ}$

  3. $35^{\circ},145^{\circ},35^{\circ},145^{\circ}$

  4. None of these


Correct Option: B
Explanation:

Since opposite angles of a parallelogram are equal. Therefore,
$3x-2=50-x\Rightarrow x=13$


$(3x−2)^{\circ}=3(13)-2=37^{\circ}$

The measures of the adjacent angles of a parallelogram add up to be $180$ degrees, or they are supplementary.
Another angle $=180-37=143^{\circ}$

The measure of each angle of the parallelogram.
$37^{\circ},143^{\circ},37^{\circ},143^{\circ}$

Find the measure of all the angles of a parallelogram, if one angle is $24^{\circ}$ less than twice the smallest angle.

  1. $68^{\circ},112^{\circ},68^{\circ},112^{\circ}$

  2. $48^{\circ},72^{\circ},48^{\circ},72^{\circ}$

  3. Insufficient data 

  4. None of these


Correct Option: A
Explanation:

Let the smallest angle be of $x^{\circ}$. 


Then, the other angle is of $(2x-24)^{\circ}$. 

Since adjacent angles of a parallelogram are supplementary.

$\therefore x^{\circ}+(2x-24)^{\circ}=180^{\circ}\Rightarrow x=68^{\circ}$


$(2x-24)^{\circ}=2(68)-24=112^{\circ}$


The measure of all the angles of a parallelogram are
$68^{\circ},112^{\circ},68^{\circ},112^{\circ}$

In a parallelogram ABCD, if $ \angle B = 135^{\circ},$ determine the measures of its other angles.

  1. $ \angle A = 45^{\circ}, \angle C = 45^{\circ},\angle D = 135^{\circ} $

  2. $ \angle A = 135^{\circ}, \angle C = 45^{\circ},\angle D = 45^{\circ} $

  3. $ \angle A = 40^{\circ}, \angle C = 50^{\circ},\angle D = 135^{\circ} $

  4. None of these


Correct Option: A
Explanation:

We have, $\angle B = 135^{\circ} $ 


Since ABCD is a parallelogram.

$ \therefore \angle A = \angle C, \angle B = \angle D $ and $ \angle A + \angle B = 180^{\circ} $

$ \Rightarrow \angle A = \angle C = 45^{\circ} $ and $ \angle B = \angle D = 135^{\circ} $

A flooring tile has the shape of a parallelogram whose base is $24: cm$ and the corresponding height is $10: cm$. How many such tiles are required to cover a floor of area $1080$ $m^2$? 

  1. $20000$

  2. $35000$

  3. $45000$

  4. $65000$


Correct Option: C
Explanation:

Area of the parallelogram $=$ Base$\times $Height


So area of each tiles $=24\times 10=240 :cm^2$

Area of the floor $=1080 : m^2=(1080\times 100\times 100)  : cm^2$

$\therefore$ Required number of tiles $=\dfrac{\text{Area of the floor}}{\text{Area of each tiles}}=\dfrac{10800000}{240}=45000$

$ABCD$ is a parallelogram of area $162\ sq. cm$. $P$ is a point on $AB$ such that $AP : PB = 1 : 2$. 
Calculate the ratio $PA : DC$.
  1. $1 : 3$

  2. $3:1$

  3. $3:2$

  4. $2:3$


Correct Option: A
Explanation:

Given,

$ABCD$ is a parallelogram, Area of parallelogram $ABCD=162cm^2$

$P$ is such a point on $AB$ such that $AP:PB=1:2$

Now, $\frac{AP}{PB}=\frac{1}{2}=k$[Let]

Thus, $AP=k$ and $PB=2k$

And, $AB=AP+PB$

   $=>AB=k+2k$

$=>AB=3k$

$\therefore \frac{AP}{AB}=\frac{1}{3}$

Now, $AB=CD$ [Opposite sides of a parallelogram are equal]

$\therefore \frac{AP}{CD}=\frac{1}{3}$


$ABCD$ is a parallelogram of area $162\: cm^2$. $P$ is a point on $AB$ such that $AP : PB = 1 : 2$. Calculate the area of $\Delta APD$
  1. $20\; cm^2$

  2. $27\ cm^2$

  3. $24\ cm^2$

  4. $25\ cm^2$


Correct Option: B
Explanation:

If $DB$ is the diagonal,
Area of parallelogram $\displaystyle \frac{1}{2}ABCD =$ area $ADB = $ area $BDC$
Area ADB$=\displaystyle \frac{1}{2} (162)=81$
$P$ is mid point of $AB$ in the ratio $1:2$ $ \left (\dfrac{1}{3}+\dfrac{2}{3}\right)$ 

Area APD $=\displaystyle \frac{1}{3}\times $ Area of $ADB=\displaystyle \dfrac{1}{3}(81)=27 $ sq. cm

The area of a parallelogram is $y$ $cm^{2}$ and its height is $h\ cm$. The base of another parallelogram is $x\ cm$ more than the base of the first parallelogram and its area is twice the area of the first. Find, in terms of $y, h$ and $x$, the expression for the height of the second parallelogram.

  1. $\displaystyle \frac{hy}{yh-x}$

  2. $\displaystyle \frac{y}{y-xh}$

  3. $\displaystyle \frac{2hy}{y+xh}$

  4. None of these


Correct Option: C
Explanation:

area of 1st parallelogram = y cm square, height = h cm

Area= Base\times Height
$y=b\times h$ ----eq 1
Base =$b=y/h$
area of 2nd parallelogram = 2y cm square, height = H cm
Base of 2nd parallelogram $\dfrac { y }{ h } +x$
$2y=(\dfrac { y }{ h }+x)\times H$
$H=\dfrac { 2yh }{ (y+hx) } $

A field is in the form of a parallelogram whose base is $420\ m$ and altitude is $3.6\ dam$. Find the cost of watering at $10$ paise per sq. m.

  1. Rs. $15.120$

  2. Rs. $1512$

  3. Rs. $151.20$

  4. None


Correct Option: B
Explanation:

Base  $= 420\ m$
Height $=  36\ m$
Area $= b \times h = 420 \times 36$
$= 15,120 \displaystyle \ m^{2}$
The cost of watering per sq m
$= 10$ paise
Cost  of watering the field $= 15120 \times 0.1$
Rs. $1512$

The base of a parallelogram is three times its height. If the area of the parallelogram is $75$ sq cm, then its height is

  1. $5 cm$

  2. $\displaystyle 5\sqrt{2}cm$

  3. $\displaystyle 3\sqrt{2}cm$

  4. $15 cm$


Correct Option: A
Explanation:

let height of ||g be 'b', then base of ||g be 3b.
 area of ||g$=$base$\times $height
$75c{ m }^{ 2 }=3b\times b\ { b }^{ 2 }=25$
 $b=5$cm, therefore height $=5$cm

A triangle and a parallelogram are constructed on the same base such that their areas are equal. If the altitude of the parallelogram is $100 m $, then the altitude of the triangle is:

  1. $100 m$

  2. $200 m$

  3. $100\sqrt{2}$ m

  4. $10\sqrt{2}$ m


Correct Option: B
Explanation:

Let the altitude of the $ \Delta =h _{1}$ and altitude of the parallelogram $  =h _{2}$ 

Let base of both $\Delta $ and parallelogram$ = b$
Then, $ b\times h _{2}=\cfrac{1}{2}\times b\times h _{1}$ 
$ \Rightarrow h _{1}=2h _{2}$
$\Rightarrow h _1 = 2\times 100m=200m$

The ratio of two adjacent sides of a parallelogram is $3 : 4$ Its perimeter is $105$ cm Find its area if altitude corresponding to the larger is $15$ cm

  1. $900$ $\displaystyle cm^{2}$

  2. $600$ $\displaystyle cm^{2}$

  3. $300$ $\displaystyle cm^{2}$

  4. $450$ $\displaystyle cm^{2}$


Correct Option: D
Explanation:

Let the two adjacent sides of the parallelogram be $3x$ and $4x$ Then
$2(3x + 4x) = 105$
$\displaystyle \Rightarrow 14x=105.$
$\displaystyle \Rightarrow x=7.5$
$\displaystyle \therefore $ The two sides are $3 \times 7.5$ cm and $4 \times 7.5$ cm 
i.e, $22.5$ cm and $30$ cm
Area of the parallelogram = base x altitude 
                                         = $30$ cm $\times$ $15$cm = $450$
$\displaystyle cm^{2}$

ABCD is a parallelogram P and R are two points on AB such that the area of parallelogram ABCD is 8 times the are of $\displaystyle \Delta DPR$ If PR = 5cm then CD is equal to 

  1. $10$ cm

  2. $5$ cm

  3. $20$ cm

  4. $12$ cm


Correct Option: C
Explanation:

Area of parallelogram ABCD 
= $8$ X Area of $\displaystyle \Delta $DPR
$\displaystyle \Rightarrow AB\times \ height=8\times \left ( \frac{1}{2}\times PR\times height \right )$
(Note: Height will be same for both the $\displaystyle \Delta $ and parallelogram)
$\displaystyle \Rightarrow  $ $AB = 4\times  PR = 4$ $\displaystyle \times  5$ cm = $20$ cm
$\displaystyle \therefore $ $\displaystyle CD = 20 $ cm

If the base of a parallelogram is $(x + 4)$, altitude to the base is $(x - 3)$ and the area is $ \displaystyle \left ( x^{2}-4 \right )$, then what is the actual area equal to?

  1. $60$ sq units

  2. $45$ sq units

  3. $77$ sq units

  4. $96$ sq units


Correct Option: A
Explanation:

Area of the parallelogram $=$ base $\times$ altitude 
$ \Rightarrow \left ( x+4 \right )\times\left ( x-3 \right )=x^{2}+4x-3x-12$
$ \displaystyle=x^{2}+x-12$
Given, $ \displaystyle x^{2}+x-12=x^{2}-4$

$\Rightarrow x=8$
$\displaystyle \therefore $Actual area $\displaystyle = \left ( 8 \right )^{2}-4 = 64 - 4 = 60$ sq units

A parallelogram whose sides are 10 cm and 5 cm has one diagonal of 8 cm, then the length of the other diagonal is

  1. 12 cm

  2. 11 cm

  3. 14 cm

  4. none of these


Correct Option: D
Explanation:

Given that, a parallelogram whose sides$l=10cm$ and$b=5cm$ has one diagonal${{d} _{1}}=8cm$.

Let, length of other diagonal $={{d} _{2}}$.


Now we know that,

  $ {{d} _{1}}^{2}+{{d} _{2}}^{2}=2\left( {{l}^{2}}+{{b}^{2}} \right) $

 $ {{8}^{2}}+{{d} _{2}}^{2}=2\left( {{10}^{2}}+{{5}^{2}} \right) $

 $ {{d} _{2}}^{2}=250-64 $

 $ {{d} _{2}}^{2}=186 $

 $ {{d} _{2}}=\sqrt{186}cm $


Hence, this is the answer. 

A parallelogram has an area of $60$ $cm^{2}$ and a base of $12$ cm. Find the height.

  1. $3$ cm

  2. $4$ cm

  3. $5$ cm

  4. $6$ cm


Correct Option: C
Explanation:

Area of a parallelogram = base $\times$ height
$60 = 12 \times height$
height = $60 \div 12$
height = $5$ cm

Find the area of a parallelogram with a base of $34$ meters and a height of $8$ meters.

  1. 262 $m^{2}$

  2. 272 $m^{2}$

  3. 282 $m^{2}$

  4. 292 $m^{2}$


Correct Option: B
Explanation:

Area of a parallelogram = base $\times$ height
= $34 \times 8$
= $272$ $m^{2}$

A parallelogram has an area of $125$ $m^{2}$ and a height of $5\ m.$ Find the base.

  1. $250$ m

  2. $25$ m

  3. $270$ m

  4. $28$ m


Correct Option: B
Explanation:

Area of a parallelogram$=base\times height$. Let the base be 'b'.
Hence
$125m^{2}=5b$ or $b=25m$
Therefore $base=25m$.

Find the base of parallelogram if its area is $\displaystyle 80{ cm }^{ 2 }$ and altitude is $10$ cm.

  1. $6$ cm

  2. $8$ cm

  3. $10$ cm

  4. None of the above


Correct Option: B
Explanation:

Area of parallelogram $\displaystyle =b\times a$
$\displaystyle 80=b\times 10$
$\displaystyle b=8cm$


So, option B is correct.

Find the area of a parallelogram with a base of $200$ cm and height of $2.5$ cm.

  1. $500$ $cm^{2}$

  2. $510$ $cm^{2}$

  3. $520$ $cm^{2}$

  4. $300$ $cm^{2}$


Correct Option: A
Explanation:

Area of a parallelogram = base $\times$ height
= $200 \times 2.5$
= $500$ $cm^{2}$

Calculate the area of a parallelogram with a base of $ 12$ m and height of $5$ m.

  1. 59 $m^{2}$

  2. 60 $m^{2}$

  3. 61 $m^{2}$

  4. 62 $m^{2}$


Correct Option: B
Explanation:

Area of a parallelogram = base $\times$ height
= $12 \times 5$
= $60$ $m^{2}$

The base and the corresponding altitude of a parallelogram are $10: cm$ and $3.5: cm$, respectively. The area of the parallelogram is

  1. $30: cm^2$

  2. $35: cm^2$

  3. $70: cm^2$

  4. $ 17.5:cm^2$


Correct Option: B
Explanation:

The area of the parallelogram is base $\times$ height $cm^2$

Area of the parallelogram$=(10)(3.5)=35:cm^2$.

If the base of a parallelogram is $8\ cm$ and its altitude is $5\ cm$, then its area is equal to

  1. $15\ cm^{2}$

  2. $20\ cm^{2}$

  3. $40\ cm^{2}$

  4. $10\ cm^{2}$


Correct Option: C
Explanation:

Area of parallelogram $=Base \times height $

$=8\times 5\ =40\ { cm }^{ 2 }$

A parallelogram has sides $30 m, 70 m$ and one of its diagonals is $80 m$ long. Its area will be

  1. $600\displaystyle m^{2}$

  2. $\displaystyle 1200\sqrt{3}m^{2}$

  3. $1200\displaystyle m^{2}$

  4. $\displaystyle 600\sqrt{3} m^{2}$


Correct Option: B
Explanation:
The diagonal of parallelogram divides it into two congruent triangles. 
$\therefore $ Area (parallelogram $ABCD) = 2 \times$ Area $ \left (\Delta ABC  \right ) $
In $ \Delta ABC$,
$ s=\cfrac{80m+ 30m+70m}{2}=\cfrac{180m}{2}=90m$
$ \therefore Area=\sqrt{90\left ( 90-80 \right )(90-30)(90-70)}m^{2}$
$ =\sqrt{90\times10\times60\times20m^{2} }$
$= 600\sqrt{3} m^{2}$

$ \therefore $ Area of parallelogram $ABCD =$$ 2\times 600\sqrt{3}m^{2}$ $ =1200\sqrt{3}m^{2}$
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