Let a line intersect the co-ordinate axes in points $A$ and $B$ such that the area of the triangle $O A B$…

Let a line intersect the co-ordinate axes in points $A$ and $B$ such that the area of the triangle $O A B$ is 12 sq. units. If the line passes through the point $(2,3)$, then the equation of the line is
  1. $x+y=5$
  2. $3 x+2 y=12$
  3. $2 x+y=7$
  4. $2 x+3 y=13$

Solution


Area of $\triangle A O B=12$ sq. units $\begin{array}{ll} & \frac{1}{2} a b=12 \\ \therefore \quad & a b=24 \\ \therefore \quad & b=\frac{24}{a}...(i) \end{array}$ Equation of line in point slope form is $\begin{aligned} & y-a=\frac{-a}{b}(x-0) \\ & y-a=\frac{-a x}{\frac{24}{a}} \end{aligned}$ ...[from (i)] $y-\mathrm{a}=\frac{-\mathrm{a}^2 x}{24}...(ii)$
Since line passes through $(2,3)$ $\begin{aligned} & \therefore \quad 3-a=\frac{-a^2(2)}{24} \\ & \quad \Rightarrow 3-a=\frac{-a^2}{12} \\ & \\ & \quad \Rightarrow a^2-12 a+36=0 \\ & \\ & \quad \Rightarrow(a-6)^2=0 \\ & \quad \Rightarrow a=6 \\ & \therefore \quad \\ & \therefore=\frac{24}{6}=4...[from(i)] \end{aligned}$ Required equation of line is $\begin{aligned} & y-6=\frac{-36 x}{24}...[from(ii)] \\ & 2 y-12=-3 x \\ & \Rightarrow 3 x+2 y-12=0 \\ & \Rightarrow 3 x+2 y=12 \end{aligned}$ ...[from (ii)]

Asked in: MHT CET 2024 (10 May Shift 1)

Practice more Straight Lines questions on Aicharya