Q. If $PQ$ and $PR$ are the two sides of a triangle, then the angle between them which gives maximum area of the triangle, is
A) $\pi$
B) $\pi/3$
C) $\pi/4$
D) $\pi/2$
Explanation
(d)
Let $PQ = a$ and $PR = b$, then $\mathrm{\Delta} = \frac{1}{2}ab\sin\theta$
$\because\ - 1 \leq \sin\theta \leq 1$
$\therefore$ Area is maximum when $\sin\theta = 1 \Rightarrow \ \ \theta = \frac{\pi}{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.