Question 1108596
This is cos^2 x(sec^2 x -1)
but sec^2 x-1 is (1/cos^2 x)-(cos^2 x/cos^2 x) or (1-cos^2x)/cos^2 x) or 
sin^2 x/cos^2 x

Therefor, this is cos^2 x* sin^2 x/cos^2 x=sin^2 x