Question

if sin (20°+∅) = cos 30°, then find the value of ∅

Answer 1

sin (20+ theta)= cos 30

Cos(90–20-theta)= cos 30

Cos(70-theta)= cos 30

70 — theta= 2n× pi + 30 or 2n × pi -30, where n belongs to all non negative integers

theta= 40 — 2n ×pi or 100 — 2n× pi

If n=0, theta = 40 degrees or 100 degrees.