1+sinx = (sinx/2+ cosx/2)^2cosx = (cosx/2 - sinx/2)(cosx/2 + sinx/2)=>(cosx/2 + sinx/2)/(cosx/2 - sinx/2) = -1/2cosx/(sinx-1) = -(cosx/2 + sinx/2)/(cosx/2 - sinx/2) = 1/2