2 -d dxcos(x∕2) sin(x∕2) = − 12-sin(x∕2) sin(x∕2)−-cos2(x∕2) sin (x∕2) cos(x∕2)1 2 = −1 2sin2(x∕2)2+cos2(x∕2) sin(x∕2) = −---12---- 2sin (x∕2)