cosA = cotA হলে A = কত?

A 0°

B 30°

C 45°

D 90°

Correct Answer: Option D

cosA = cotA
বা, cosA = cosA/sinA
বা, 1 = 1/sinA
বা, sinA = 1
বা, sinA = sin90°
∴ A = 90°