Q. In a $\mathrm{\Delta}\ ABC,\ \angle\ A = \frac{\pi}{2}$, then $\cos^{2}{B + \cos^{2}C}$ equals
A) $- 2$
B) $- 1$
C) 1
D) 0
Explanation
(c)
$\cos^{2}{B + \cos^{2}{C = \cos^{2}{B + \cos^{2}\left( \frac{\pi}{2} - B \right)}}}$
$= \cos^{2}{B + \sin^{2}{B = 1}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.