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##