In Exercises 1-4, verify the identity. 1. sin 1/2 x cos x - sin 5/2 x cos

Question:

In Exercises 1-4, verify the identity.
1. sin 1/2 x cos x - sin 5/2 x cos x = cos3 x √sin x
2. sec6 x(sec x tan x) - sec4 x(sec x tan x) = sec5 x tan3
3. (1 + sin y) [1 + sin(-y)] = cos2y
4. tan x + tan y / 1 - tan x tan y = cot x + cot y / cot x cot y - 1