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Family of Lines - Practice Questions & MCQ

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #JEE Main

Quick Facts

  • Family of Lines is considered one of the most asked concept.

  • 21 Questions around this concept.

Solve by difficulty

If the lines 3y + 4x = 1, y = x + 5 and 5y + bx = 3 are concurrent, then the value of b is

 

A line which makes an acute angle \mathrm{\theta } with the positive direction of the \mathrm{ x-axis } is drawn through the point \mathrm{ P(3, 4) }, to cut the curve \mathrm{ y^2 = 4x} at \mathrm{ Q}  and \mathrm{R}. The lengths of the segments \mathrm{PQ}  and \mathrm{PR} are numerical values of the roots of the equation \mathrm{r2} \mathrm{sin2} \mathrm{\theta }  \mathrm{ + 4r } \mathrm{\left ( 2 sin \theta - cos \theta \right )} \mathrm{+ c } \mathrm{= 0, } where \mathrm{c = }

If \mathrm{4 a^2+9 b^2-c^2+12 a b=0}, the family of straight lines \mathrm{a x+b y+c=0} is either concurrent at

If \mathrm{a, b, c} are in H.P. then the straight line \mathrm{\frac{x}{a}+\frac{y}{b}+\frac{1}{c}=0} passes through a point, that point is

Consider a family of straight lines \mathrm{(x+y)+\lambda(2 x-y+1)=0}. The equation of the straight line belonging to this family that is the farthest form (1,-3) is

Concepts Covered - 1

Family of Lines

Family of Lines

Any equation of line through the point of intersection of the lines $L_1=a_1 x+b_1 y+c_1=0$ and $L_2=a_2 x+b_2 y+c_2=0$ can be represented as

$
\begin{aligned}
& \mathrm{a}_1 \mathrm{x}+\mathrm{b}_1 \mathrm{y}+\mathrm{c}_1+\lambda\left(\mathrm{a}_2 \mathrm{x}+\mathrm{b}_2 \mathrm{y}+\mathrm{c}_2\right)=0 \\
& \text { or, } \mathrm{L}_1+\lambda \mathrm{L}_2=0
\end{aligned}
$


Where $\lambda$ is a parameter.

 

 

Note:.

  • The equation L1 + λL2 = 0 or μL1 + νL2 = 0  represents a line passing through the intersection of the lines L1 = 0 and L2 = 0 which is a fixed point. And λ,  μ , ν are constants.

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Family of Lines

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Family of Lines

Mathematics for Joint Entrance Examination JEE (Advanced) : Coordinate Geometry

Page No. : 2.25

Line : 5

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