Question
If tan 2A = cot (A - 18°), where 2A is an acute angle, find the value of A.
Solution
tan 2A = cot (A - 18°) =
cot (90° - 2A) = cot (A-18°)
⇒90° - 2A = A - 18°
⇒-3A = -108°
⇒A = 36°.
