In Exercises 1-4, verify the identity.
1. tan t cot = 1
2. tan x cot x / cos x =sec x
3. (1 + sin α)(1 − sin α) = cos2 α
4. cos2β − sin2β = 2 cos2 β - 1
5. cos2β − sin2 β = 1 − 2 sin2 β