Question

Find the value of x, if cos x = cos 60° cos 30° – sin 60° sin 30°

Answer 1

cos x = cos 60° cos 30° – sin 60° sin 30°

cos x = ${\displaystyle \left(\frac{1}{2}\right)\left(\frac{\sqrt{3}}{2}\right)-\left(\frac{\sqrt{3}}{2}\right)\left(\frac{1}{2}\right)}$

cos x = 0 = cos 90°

Hence, x = 90°