Prove that cos² A + cos²(A + 120^o) + cos²(A -120^o) = \(\frac{3}{2}\)

Show that sin20^osin 40^o sin 60^o sin80^o = \(\frac{3}{16}\)

Convert the following into the product of trigonometric functions sin7\(\theta\) - sin4\(\theta\)

Convert the following into the product of trigonometric functions cos4\(\alpha\) - cos8\(\alpha\)

Convert the following into the product of trigonometric functions cos75^o + cos 45^o