cscx-cotx*cosx=sinx A few transformations we can make based on trig identities: csc(x) = 1/sin(x) cot(x) = cos(x)/sin(x) So we have: 1/sin(x) - cos(x)/sin(x) * cos(x) = sin(x) (1 - cos^2(x))/sin(x) = sin(x) 1 - cos^2(x) = sin^2(x) This is true from the identity: sin^2(x) - cos^2(x) = 1