Question

Select all of the given trigonometric equations that are true statements. sin(180°) = cos(0°) cos(74°) = sin(16°) sin(20°) = cos(70°) sin(A°) = cos(90° - A°) sin(A°) = cos(180° - A°) cos(140°) = sin(40°)

Answer 1

Cos 74°= Sin 16°

Sin 20°= Cos 70°

Sin A°=Cos (90°- A°)

Explanation:

This is because the three pairs are complementary i.e they add up to 90° and in trigonometric ratios, complementary ratios are equal.