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Basics of a straight line - class-X

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If the straight line through the point $P(3,4)$ makes an angle $\cfrac{\pi}{6}$ with the x-axis and meets the line $3x+5y+1=0$ at $Q$, the length $PQ$ is

  1. $\dfrac {132}{12\sqrt {3}+5}$

  2. $\dfrac {132}{12\sqrt {3}-5}$

  3. $\dfrac {132}{5\sqrt {3}+12}$

  4. $\dfrac {132}{5\sqrt {3}-12}$


Correct Option: D
Explanation:

The equation of straight line passing through $P(3,4)$ is $y=\tan \dfrac{\pi}{6}{x}+(4-3\tan \dfrac{\pi}{6})\implies y=\dfrac{x}{\sqrt{3}}+4-\sqrt{3}$

The point of intersection will be $\bigg(\dfrac{55-57\sqrt{3}}{5+3\sqrt{3}},\dfrac{-10+3\sqrt{3}}{5+3\sqrt{3}}\bigg)$
Length will be $30(5-3\sqrt{3})$

If $m$ and $b$ are real numbers and $mb > 0$, then the line whose equation is $y = mx + b$ cannot contain the point-

  1. $(0, 2009)$

  2. $(2009, 0)$

  3. $(0, -2009)$

  4. $(20, -100)$


Correct Option: B
Explanation:
$y= mx + b$
for (2009,0)
substituting in the given line
we get $2009m+b=0$
that is possible only if $mb < 0$
which contradicts our initial assumption mb > 0
so option is $b$

The graph of $\dfrac {7x}{2}=18+\dfrac {4}{5}x-45$ is line____

  1. Parallel to $x-$axis at a distance of $10$ units from the origin

  2. Parallel to $y-$axis at a distance of $10$ units from the origin

  3. Parallel to $x-$axis at a distance of $20$ units from the origin

  4. Parallel to $y-$axis at a distance of $20$ units from the origin

  5. None of these


Correct Option: B
Explanation:

$\cfrac { 7x }{ 2 } =18+\cfrac { 4 }{ 5 } x-45\ \Rightarrow \cfrac { 7x }{ 2 } -\cfrac { 4x }{ 5 } =-27\ \Rightarrow \cfrac { 35x-8x }{ 10 } =-27\ \cfrac { 27x }{ 10 } =-27\ \Rightarrow x=-10$

Therefore graph is a straight line parallel to y-axis at a distance of $10$ units from the origin.

Find $c$ if the line $cx+5y-3=0$ passes through $(2,1)$

  1. -1

  2. -2

  3. 3

  4. 4


Correct Option: A
Explanation:

Point is $(2,1)$

Equation is $cx+5y-3=0\c(2)+5(1)-3=0\2c+2=0\c=-1$

The graph of the equation y = mx is line which always passes through

  1. (0, m)

  2. (x, 0)

  3. (0, x)

  4. (0, 0)


Correct Option: D
Explanation:

The graph is shown in image 

$y=mx$
Given lines always passes through $(0,0)$ for any value of $m$ 
Because $(0,0)$ always satisfied the equation $y=mx$

Equation y = 2x + 5 has

  1. unique solution

  2. no solution

  3. only two solutions

  4. infinitely many solution


Correct Option: D
Explanation:

$ y=2x+5$ is an equation of line which satisfied many value of $x$ and $y$ 


Hence this equation has infinitely many solutions 

The equation  of a line is given by $3x - 2y = 9$ has how many possible solution?

  1. One solution

  2. No solution

  3. Two solution

  4. Infinitely many solution


Correct Option: D

Which of the following is TRUE regarding the graphs of the equations of a linear quadratic system?

  1. the graphs may intersect in two locations

  2. the graphs may intersect in one location

  3. the graphs may not intersect

  4. all three choices are true

  5. none of these


Correct Option: D
Explanation:

Option D is correct.

The number of triangles that the four lines $y=x+3$, $y=2x+3$, $y=3x+2$, and $y+x=3$ form is?

  1. $4$

  2. $2$

  3. $3$

  4. $1$


Correct Option: A
Explanation:

The given lines are $y=x+3, y=2x+3, y=3x+2$ Vand $y+x=3$ and $y+x=3$

Slopes of these lines are different from each other 
So, combinations of $3$ lines form a triangle 
$\therefore$ Number of triangles formed $=\, ^4C _3$
                                                   $=4$

If sum of distance of a point from two perpendicular lines in a plane is $1$, then its locus is ?

  1. Square

  2. Circle

  3. A straight line

  4. An intersecting line


Correct Option: A
Explanation:

Let x axis & y axis are the perpendicular lines. The sum of the distances from point $p(x, y)$ is $1$ 

i.e.,$|x| + |y| = 1$

The locus of the point 'p' which is the rhombus whose sides are $x + y = 1 ; -x + y = 1 ; x - y = 1 ; -x - y = 1$

$\bot r$ lines other than coordinate axis gives same result so locus is a square. 

The nearest point on the line $3x-4y=25$ from the origin is

  1. $(-4,5)$

  2. $(3,-4)$

  3. $(3,4)$

  4. $(3,5)$


Correct Option: B
Explanation:

Distance of the line $3x-4y-25=0$ from the origin is 
$\displaystyle d=\frac{|-25|}{\sqrt{25}}$
$\Rightarrow d=5$
Only the point given in option B lies on the given line .
Also, its distance from origin is 5.
So, (3,-4) is the nearest point on the line from the origin.

Consider the lines $2x+3y=0$,    $5x+4y=7$. Find the intersection point.

  1. $(3,-2)$

  2. $(3,2)$

  3. $(-3,2)$

  4. $(2,3)$


Correct Option: A
Explanation:

The lines are $2x+3y=0$......(1)


$x=\dfrac{-3y}{2}$

$5x+4y=7$........(2)

$5\left(\dfrac{-3y}{2}\right)+4y=7$

$-15y+8y=14$

$-7y=14$

$y=-2$

$x=\dfrac{-3(-2)}{2}=3$

$(x,y)=(3,-2)$

Examine whether the point (2, 5) lies on the graph of the equation $3x\, -\, y\, =\, 1$.
State true or false.

  1. True

  2. False


Correct Option: A
Explanation:

Put x = 2 and y = 5 in the equation,
3x - y = 1
6 - 5 = 1
1 = 1
Hence, the point lies on the equation.


$y=2x+3$
Which of the following statements is true about the given line?

  1. The line passes through $(0,3)$ and $m=-2$

  2. The line passes through $(3,0)$ and $m=-2$

  3. The line passes through $(0,3)$ and $m=2$

  4. The line passes through $(3,0)$ and $m=2$


Correct Option: C
Explanation:

Comparing the given equation $y=2x+3$ with $y = mx+c$, we get

Hence, $m=2$ and $c=3$.
So, options A and B are incorrect.

Option C:
Substitute $(0,3)$ in the given equation, we get
RHS: $=2(0)+3 = 3$
LHS: $y=3$
$LHS =  RHS$, Hence option C is correct.

Option D:
Substitute $(3,0)$ in the given equation, we get
RHS: $=2(3)+3 = 9$
LHS: $y=0$

$LHS \neq RHS$. Hence, option D is incorrect.

Consider the equation of the line :$\displaystyle \frac{x-1}{3}-\frac{y+2}{2}=0$

  1. The line passes through $(4,0)$  and $m=2/3$

  2. The line passes through $(4,0)$  and $m=-2/3$

  3. The line passes through $(4,0)$  and $m=3/2$

  4. The line passes through $(4,0)$  and $m=-3/2$


Correct Option: A
Explanation:
Given line 
$\dfrac{x-1}{3}-\dfrac{y+2}{2}=0$

$\dfrac{x-1}{3}=\dfrac{y+2}{2}$

$2(x-1)=3(y+2)$

$2x-2=3y+6$

$y=\dfrac{2x}{3}-\dfrac{8}{3}$

on comparing above eq with $y=mx+c$

$slope(m)=\dfrac{2}{3}$

y-intercept$=-\dfrac{8}{3}$

when $y=0,x=4$

Hence it passes through $(4,0)$ with $m=\dfrac{2}{3}$

Consider the line: y= -x +4

Which of the following is correct.

  1. The line passes through (0,4) and m=1.

  2. The line passes through (0,4) and m=-1.

  3. The line passes through (0,0) and m=-1.

  4. The line passes through (4,0) and m=-1.


Correct Option: B
Explanation:
Given line 
$y=-x+4$
on comparing above eq with $y=mx+c$
$slope(m)=-1$
y-intercept$=4$
Hence it passes through (0,4) with $m=-1$

Draw the graph for each linear equation:
$\displaystyle y=\frac{3}{2}x+\frac{2}{3}$

  1. The line passes through $(4/9,0)$ and $m=-\dfrac32$

  2. The line passes through $(-0.4/9,0)$ and $m=\dfrac32$

  3. The line passes through $(-4/9,0)$ and $m=\dfrac32$

  4. The line passes through $(-0.9/4,0)$ and $m=-\dfrac32$


Correct Option: C
Explanation:

The given line equation is $\frac{3}{2}x-y+\frac{2}{3}$

The slope of given line is $-(\frac { \frac { 3 }{ 2 }  }{ -1 } )=\frac { 3 }{ 2 } $
If we put $y=0$ , then the value of $x= -\frac{4}{9}$
Therefore line passes through $(-\frac{4}{9},0)$ and slope is $\frac{3}{2}$
So the correct option is $C$

Consider the equation of the line $\displaystyle x-3=\frac{2}{5}\left ( y-1 \right )$. Which of the following is correct?

  1. The line passes through $(6,5)$  and $m=-2/5$.

  2. The line passes through $(5,6)$  and $m=-5/2$.

  3. The line passes through $(6,5)$  and $m=2/5$.

  4. The line passes through $(5,6)$  and $m=5/2$.


Correct Option: D
Explanation:
Given line 
$x-3=\dfrac{2}{5}(y-1)$
$5(x-3)=2(y-1)$
$5x-15=2y-2$
$2y=5x-13$
$y=\dfrac{5x}{2}-\dfrac{13}{2}$
on comparing above eq with $y=mx+c$
$slope(m)=\dfrac{5}{2}$

when $x=5$
$2y=25-13$
$2y=12$
$y=6$
Hence it passes through (5,6) with $m=\dfrac{5}{2}$

For the pair of linear equations given below, draw graph and then state, whether the lines drawn are,
$\displaystyle y=3x-1$
$\displaystyle \frac{x}{2}+\frac{y}{3}=1$

  1. Perpendicular

  2. Parallel

  3. Intersecting but not at right angles

  4. Options B & C


Correct Option: C

For the pair of linear equations given below, draw graphs and then state, whether the lines drawn are 
$\displaystyle 3x+4y=24$
$\displaystyle \frac{x}{4}+\frac{y}{3}=1$

  1. intersecting but not at right anglesl

  2. Options B & D

  3. perpendicular

  4. parallel


Correct Option: D

The straight lines given by the equations $\displaystyle x+y=2 , x-2y=5 \ and \ \frac{x}{3}+y=0$ are?

  1. concurrent

  2. intersecting to make a right triangle.

  3. intersecting to make an isosceles triangle.

  4. parallel to each other.


Correct Option: A
Explanation:
Given lines
$x+y=2$------(1)
$x-2y=5$----(2) and $\dfrac{x}{3}+y=0$----(3)
Solving eq (1) and (2)
$x-2(2-x)=5$
$x-4+2x=5$
$x=3$ and $y=2-3=-1$
Point of intersection of line (1) and (2) is $P(3,-1)$
Solving eq (2) and (3)
$-3y-2y=5$
$-5y=5$
$y=-1$ and $x=-3y=3$
Point of intersection of line (2) and (3) is $Q(3,-1)$
Solving eq (1) and (3)
$-3y+y=2$
$-2y=2$
$y=-1$ and $x=-3y=3$
Point of intersection of line (1) and (3) is $R(3,-1)$
Here point of intersection of all line is same Hence line is concurrent

If the line ax + by + c = 0 is such that  a = 0 and b, $\displaystyle c\neq 0$ then the line is perpendicular to 

  1. x-axis

  2. y-axis

  3. x + y =1

  4. x = y


Correct Option: B
Explanation:

When $ a= 0 $ then the line equation becomes $ by + c = 0 $ or $ y = -\frac {c}{b} $

Equations of the form $ y =k $ are parallel to x-axis. This also means that they are perpendicular to $ y - $ axis as $ x-$ axis and $ y- $axis are perpendicular to each other.

Find the equation of a line passing through the point (2, -3 ) and parallel to the line 2x - 3y + 8 = 0

  1. 2x - 3y =13

  2. 2x -3y = 12

  3. x - 3y =4

  4. 3x - 2y = 7


Correct Option: A
Explanation:

Equation of the line parallel to $ 2x-3y+8 = 0 $ will be of the form $ 2x-3y + k = 0 $

Now, since it passes through $ (2,-3) $, on substituting it , we get $ 2(2) -3(-3) + k = 0  $
$ => k = -13 $

So, required eqn of parallel line is $ 2x - 3y - 13 = 0 $

$\dfrac {a}{3} + \dfrac {b}{6} = 1$
If $a$ and $b$ are positive integers in the equation above, then what is the value of $a b$?

  1. $4$

  2. $2$

  3. $6$

  4. $8$

  5. $5$


Correct Option: A
Explanation:

Given eq 

$\dfrac{a}{3}+\dfrac{b}{6}=1$
$2a+b=6$---(1)

putting $a=1$ in eq (1)
$b=4$
Hence $ab=4$

If $y$ is directly proportional to $x$ and if $y=20$  when $x=6$, what is the value of $y$ when $x=9$?

  1. $\displaystyle\frac{10}{3}$

  2. $\displaystyle\frac{40}{3}$

  3. $23$

  4. $27$

  5. $30$


Correct Option: E
Explanation:

Given that: $'y'$ is directly proportional to $'x'$,

Formally, it is expressed as
$y$ $=$ $k$$x$   where, $'k'$ is a constant
To find the value of $'k'$,
As $y$ $=$ $20$  when  $x$ $=$ $6$,
$\Rightarrow y$ $=$ $k$$x$
$\Rightarrow y$ $=$ $k$ $\times$ $x$
$\Rightarrow 20$ $=$ $k$ $\times$ $6$
$\Rightarrow k$ $=$ $\dfrac {20}{6}$
$\Rightarrow k$ $=$ $\dfrac {10}{3}$
Now, $y$ $=$ $\dfrac {10}{3}$$x$
To find $'y'$ when $x$ $=$ $9$,
$\Rightarrow y$ $=$ $\dfrac {10}{3}$$x$
$\Rightarrow y$ $=$ $\dfrac {10}{3}$ $\times$ $x$
$\Rightarrow y$ $=$ $\dfrac {10}{3}$ $\times$ $9$
$\Rightarrow y$ $=$ $30$

Therefore, the value of $'y'$ when $x$ $=$ $9$ is $'30'$.

If $y=2x+3$ and $x < 2$, which of the following represents all the possible values for $y$?

  1. $y < 7$

  2. $y > 7$

  3. $y < 5$

  4. $y > 5$

  5. $5 < y < 7$


Correct Option: A
Explanation:

Given, $y$ $=$ $2x$ $+$ $3$ and $x$ $<$ $2$

To find possible values for $y$,
$\Rightarrow 2x$ $=$ $y$ $-$ $3$
$\Rightarrow x$ $=$ $\dfrac {y \space - \space 3}{2}$
As $x$ $<$ $2$,
$\Rightarrow \dfrac {y \space - \space 3}{2}$  $<$ $2$
$\Rightarrow y$ $-$ $3$ $<$ $4$
$\Rightarrow y$ $<$ $7$
Therefore, possible values for $'y'$ are $'y$ $<$ $7'$.

The graph of equation of the form $ax + by +c=0$ where a, b are non $-$ zero numbers,
represents:

  1. A triangle

  2. A ray

  3. A straight line

  4. a line segment


Correct Option: C
Explanation:

The equation $ax+by+c=0$ represent straight line under one condition i. e, 

$|a|+|b|\neq 0$       or,     $ a\neq b\neq 0$
Also,  here
$y= \dfrac{-a}{b}x$ $  \dfrac{-c}{b}$ represent the slope interspect form where $m= (-a/b), y-m =  -c/b $ 

A right-angled triangle is formed by a straight line : $3x-4y=12$ with both the axis. Then length of perpendicular from the origin to the hypotenuse is :

  1. $3.5$

  2. $2.4$

  3. $4.2$

  4. none of these


Correct Option: B
Explanation:

Given straight line is $3x-4y=12$
$\Rightarrow\frac{x}{4}-\frac{y}{3} = 1$
this line have x intercept y & y- intercept (-3)
so the evaluation of hypotenuse s the given straight line $3x-4y=12$
so, distance of O(0, 0) form the line $3x-4y=12$ is given by
$=\frac{|3\times0-4\times0-12|}{\sqrt{(3)^2+(-4)^2}}$
$=\frac{12}{5}$
$=2.4$

The graph of the function $\displaystyle \cos x.\cos (x+2)-\cos^{2}(x+1)$ is a 

  1. straight line passing through the point $\displaystyle(0,-\sin^{2}1)$ with slope $2$

  2. straight line passing through the origin

  3. parabola with vertex $\displaystyle (1,-\sin^{2}1)$

  4. straight line passing through the point $\displaystyle\left(\dfrac{\pi}2,-\sin^{2}1\right) $ and parallel to the $x-$axis


Correct Option: D
Explanation:

Let $y=\cos { x } \cos { \left( x+2 \right)  } -\cos ^{ 2 }{ \left( x+1 \right)  } \ =\cos { \left( x+1-1 \right)  } \cos { \left( x+1+1 \right)  } -\cos ^{ 2 }{ \left( x+1 \right)  }\$
 Using $\cfrac{1}{2} \left[\cos\left(A+B+A-B\right)+\cos\left(A+B-A+B\right)\right]\
           = \cfrac{1}{2}\left[\cos 2A + \cos 2B\right]
           = \cfrac{1}{2}\left[\cos^{2}A -1 +1 -2 \sin^{2}A\right ]
           =  \cos ^{2}\left(x+1\right)-\sin^{2}1 $
$=\cos ^{ 2 }{ \left( x+1 \right)  } -\sin ^{ 2 }{ 1 } -\cos ^{ 2 }{ \left( x+1 \right)  } \ =-\sin ^{ 2 }{ 1 } $
This is a straight line which is parallel to x-axis, it passes through $\left( \cfrac { \pi  }{ 2 } ,-\sin ^{ 2 }{ 1 }  \right) $

Complete the table, to draw the graph of line $2y=3x+2$.


$x:$ $3$ $\displaystyle \frac{7}{3}$ $-2$
$y:$ $y _1$ $y _2$ $y _3$

  1. $y _1 = \dfrac12, y _2=\dfrac72,y _3 = -2$

  2. $y _1 = \dfrac{11}2, y _2=\dfrac92,y _3 = -2$

  3. $y _1 = \dfrac12, y _2=\dfrac72,y _3 = -3$

  4. $y _1 = \dfrac{11}2, y _2=\dfrac92,y _3 = -3$


Correct Option: B
Explanation:

The equation of line is $2y=3x+2$

Now to complete the given table,
Substitute $x=3$ in the equation $2y=3x+2$ to fill the first column of the table
$\displaystyle 2y _1=3\times 3+2\ \Rightarrow 2y _1=9+2\ \Rightarrow 2y _!=11\ \Rightarrow y _!=\dfrac { 11 }{ 2 }$
 Substitute $x=\dfrac { 7 }{ 3 }$ in the equation $2y=3x+2$ to fill the second column of the table

$2y _2=3\times \dfrac { 7 }{ 3 } +2\\ \Rightarrow 2y _2=7+2\\ \Rightarrow 2y _2=9\\ \Rightarrow y _2=\dfrac { 9 }{ 2 }$
Finally, substitute $x=-2$ in the equation $2y=3x+2$ to fill the first column of the table
$2y _3=3\times -2+2\\ \Rightarrow 2y _3=-6+2\\ \Rightarrow 2y _3=-4\\ \Rightarrow y _3=-2$

Which of the following is true about the three lines
$L _{1}: x - 3y + 7 = 0 , L _{2} : 2x + y - 3 = 0$ and $L _{3} : 7x +\dfrac{7y}{2}-\dfrac{21}{2}=0$

  1. Lines form a triangle

  2. Lines are concurrent

  3. Lines can not bound any region

  4. None of these


Correct Option: C
Explanation:

Given equations of lines as
$L _{1}: x - 3y + 7 = 0 $
Slope of $L _{1}=\displaystyle \frac{1}{3}$
$ L _{2} : 2x + y - 3 = 0$ 
Slope of $L _{2}=-2$
$L _{3} : 7x +\dfrac{7y}{2}-\dfrac{21}{2}=0$
Slope of $L _{3}=-2$
$\Rightarrow L _{2}$ and $L _{3}$ are parallel
Hence, lines cannot bound any region.

The number of circles that touch all the straight
lines $x+y - 4 = 0, x - y+2 = 0$ and $y = 2$ is

  1. 1

  2. 2

  3. 3

  4. 4


Correct Option: D
Explanation:

The given lines form a triangle.
The number of circles are $4$, i.e. incircle and three ex-circles of the triangle. 

The points (4,0), (0,4), (-4,0), and (0, -4) form

  1. a rectangle

  2. a square

  3. a trapezium

  4. none of these


Correct Option: B
Explanation:

From the diagram the points form a square

Find the equation of the straight line passing through the point $ (6,2)  $ and having slope $ -3 .  $

  1. $x-3y-10=0$

  2. $3x+y-20=0$

  3. $x+2y-40=0$

  4. $3x-y-10=0$


Correct Option: B
Explanation:

Equation of any line is $y=mx+c$


here $m$ is slope of line 


so we have $m=-3$

$y=-3x+c$

Also this line passes through $(6, 2)$

$2=-18+c\Rightarrow c=20$

so equation of line will be $y+3x=20$

or $3x+y-20=0$.


A line passing through (2, 2) is perpendicular to the line $3x+y=3$. Its y intercept is _____________.

  1. $\dfrac { 1 }{ 3 } $

  2. $\dfrac { 2 }{ 3 } $

  3. 1

  4. $\dfrac { 4 }{ 3 } $


Correct Option: A
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