Gujarati
9.Straight Line
medium

The equation of the line which makes right angled triangle with axes whose area is $6$ sq. units and whose hypotenuse is of $5$ units, is

A

$\frac{x}{4} + \frac{y}{3} = \pm \;1$

B

$\frac{x}{4} - \frac{y}{3} = \pm \;3$

C

$\frac{x}{6} + \frac{y}{1} = \pm \;1$

D

$\frac{x}{1} - \frac{y}{6} = \pm \;1$

Solution

(a) If the line is $\frac{x}{a} + \frac{y}{b} = 1$, then the intercepts on the axes are $a$ and $b$.

Therefore the area is $\frac{1}{2}|a \times b| = 6 \Rightarrow |ab| = 12$ …..$(i)$

and hypotenuse is $5$, therefore ${a^2} + {b^2} = 25$ …..$(ii)$

On solving $(i)$ and $(ii)$, we get

$a = \pm 4$or $ \pm 3$and $b = \pm 3$or $ \pm 4$

Hence equation of line is $ \pm \frac{x}{4} \pm \frac{y}{3} = 1$or $ \pm \frac{x}{3} \pm \frac{y}{4} = 1$.

Trick: Check with options. Obviously, the line $\frac{x}{4} + \frac{y}{3} = \pm 1$ satisfies both the conditions.

Standard 11
Mathematics

Similar Questions

Start a Free Trial Now

Confusing about what to choose? Our team will schedule a demo shortly.