How do you simplify (1-cos^2x)/sinx?

Use ##cos^2 x + sin^2 x = 1## to find:
##(1-cos^2 x)/(sin x) = sin x##
Since ##cos^2 x + sin^2 x = 1## we find:
##(1-cos^2 x)/(sin x) = (sin^2 x)/(sin x) = sin x##