If A = 30°, then prove that : sin 2A = 2 sin A cos A = 2 tan A/1 + tan^2 A

∴ 1st term = 2nd term = 3rd term Hence, .

Given A = 60° and B = 30°, prove that :
cos (A - B) = cos A cos B + sin A sin B

If A = 30°, then prove that :
2 cos² A - 1 = 1 - 2 sin² A