Q. If $- \pi \leq x \leq \pi,\ - \pi \leq y \leq \pi\ and\cos{x + \cos{y = 2}}$, then the value of $cos(x - y)$ is
A) $- 1$
B) 0
C) 1
D) None of these
Explanation
(c)
Maximum value of $\cos{\theta = 1}$
So, the equation can have solution only when
$\cos{x = 1,\ \cos{y = 1}}$
$\Rightarrow \ x = 0,\ y = 0$
$\Rightarrow \ \cos{(x - y) = \cos{0 = 1}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.