Q. The value of $\cos{(270{^\circ} + \theta)}\cos{(90{^\circ} - \theta)} - \sin{(270{^\circ} - \theta)\cos\theta}$ is
A) 0
B) $- 1$
C) 1/2
D) 1
Explanation
(d)
$\cos{(270{^\circ} + \theta)\left( \cos{90{^\circ} - \theta} \right) - \sin{(270{^\circ} - \theta)}\cos\theta}$
$= \sin{\theta.\sin{\theta + \cos{\theta.\cos\theta}}}$
$= \sin^{2}{\theta + \cos^{2}{\theta = 1}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.