Q. The least value of $cosec^{2}x + 25\sec^{2}x$ is
A) 0
B) 26
C) 28
D) 36
Explanation
(d)
$cosec^{2}x + 25\sec^{2}{x = 26 + \cot^{2}{x + 25\tan^{2}x}}$
$= 26 + 10 + \left( \cot{x - 5\tan x} \right)^{2} \geq 36$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.