Question

Simplify the square root of (1-cos theta)(1+cos theta)

Answer 1

hello : 
(1-cos(θ))(1+cos(θ)) = 1-cos²((θ)
but : cos²(θ) +sin²(θ) = 1 
1- cos²(θ) = sin²(θ)
(1-cos(θ))(1+cos(θ)) = 1-cos²((θ) = sin²(θ)