Question

If sec 4A = cosec (A – 20°) where 4A is an acute angle, find the value of A.

Answer 1

sec 4A = sec [90 − 𝐴 − 20] [∵ sec(90 − θ) = cosec θ]

sec 4A = sec (90 – A + 20)

sec 4A = sec (110 – A)

4A = 110 – A

5A = 110

`A = 110/5 => A = 22`