sinX sinY = (1/2) [ cos (X - Y) - cos (X + Y) ]
so y = 1/2 [(cos pi/3) - cos(2x-pi/3)]
= 1/4 - 1/2 cos(2x-pi/3)
maximum is 1/4
sinX sinY = (1/2) [ cos (X - Y) - cos (X + Y) ]
so y = 1/2 [(cos pi/3) - cos(2x-pi/3)]
= 1/4 - 1/2 cos(2x-pi/3)
maximum is 1/4