In Exercises 1-4, use trigonometric identities to transform the left side of the equation into the right side (0 < < / 2).

In Exercises 1-4, use trigonometric identities to transform the left side of the equation into the right side (0 < θ < π / 2).
1. tan  θ cot θ  = 1
2. cos θ sec θ = 1
3. tan α cos α = sin α
4. cot α sin α = cos α