Cos A - sin A = 0.2
(Cos A - SinA)^2 = 0.04
Cos^2 A - 2sinA*cosA + sin^2 A = 0.04
sinA*cosA = (cos^2 A + sin^2 A - 0.04 ) / 2 = (1 - 0.04) / 2 = 0.48
=)
