Equation of a Line Through Two Intersecting Lines' Point of Intersection

Rarely Tested

Equation of a Line Through Two Intersecting Lines' Point of Intersection

## Formula

If $$L_1=0$$ and $$L_2=0$$ intersect at a point, the general line through their point of intersection is:

$$L_1+\lambda L_2=0$$

## Terminologies

- $$\lambda$$ → Arbitrary real parameter.

- $$L_1,L_2$$ → Equations of the two given lines.

## Usage

- Used to represent every line passing through the common point of two intersecting lines.

Question 1

Consider the family of straight lines(3x + 2y − 10) + λ(x − 2y) = 0, λ ∈ ℝ. All members of this family pass through a fixed point P. The member of this family that makes an angle of 45° with the line 5x − y + 4 = 0 and has a negative slope is chosen.

The sum of the absolute values of the x-intercept and y-intercept of this chosen line is:

Question 2

Consider the variable line $$x(3\lambda + 1) + y(7\lambda + 2) = 17\lambda + 5$$, where $$\lambda$$ is a real parameter. All such lines pass through a fixed point $$P$$. Let $$L$$ be the specific line from this family that is farthest from the origin. If the distance of $$L$$ from the point $$(3, 6)$$ is $$d$$, then the value of $$d^2$$ is:

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