How do you verify ##(1+cosx)/(1-cosx) - (1-cosx)/(1+cosx)=4cotxcscx##?

Verify trig expression.

Develop left side numerator: ##(1 + cos x)^2 - (1 - cos x)^2 = 4cos x## Develop left side denominator: ##(1 - cos x)(1 + cos x) = (1 - cos^2 x) = sin^2 x.## Full left side: ##(4cos x)/sin^2 x = 4(cos x/sin x) (1/sin x) = 4cot x.csc x##