Question

If tan2a=cos(A - 18°),where 2A is an acute angle, find the value of A

Answer 1

Heya !!

Here is your answer..

Since , Tan A = cot ( 90° - 2A )

Therefore,Cot(90°-2A) = cot(A-18°)

==> 90° - 2A = A -18°

==> 90° + 18° = A + 2A

==> 108° = 3A

==> A = 36°

Hope it helps.

Answer 2

Given : tan 2A = cot(A – 18)°

cot(90 – 2A) = cot(A – 18)°

90 – 2A = A – 18

– 2A – A = – 18 – 90

– 3A = – 108

A = $\bf\huge\frac{-108}{-3}$

A = 36