Question

Find the exact value of cos 75 by using a sum or difference formula

Answer 1

Cos 75 = 45 + 30

Formula: cos 45 x cos 30 - sin 45 x sin 30

Cos 45 = root 2 / 2
Cos 30 = root 3 / 2
Sin 45 = root 2 / 2
Sin 30 = 1 / 2