Q. $\sin^{2}{17.5{^\circ} + \sin^{2}{72.5{^\circ}}}$ is equal to
A) $\cos^{2}{90{^\circ}}$
B) $\tan^{2}{45{^\circ}}$
C) $\cos^{2}{30{^\circ}}$
D) $\sin^{2}{45{^\circ}}$
Explanation
(b)
$\sin^{2}{17.5{^\circ} + \sin^{2}{72.5}}{^\circ}$
$= \sin^{2}{17.5{^\circ} + \cos^{2}{17.5{^\circ}\ \ \ \ \lbrack\because\ \sin{(9\theta - \theta) = \cos\theta}\rbrack}}$
$= 1 = \tan^{2}{45{^\circ}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.