2sin75°cos75°=sin(2x75°)=sin150°=sin30°=1/2
2cos^2π/8-1=cos(2π/8)=cos(π/4)=cos45°
2cos^2(150°)-1=cos(2x150°)=cos300°=-cos60°=-1/2
2sin75°cos75°=sin(2x75°)=sin150°=sin30°=1/2
2cos^2π/8-1=cos(2π/8)=cos(π/4)=cos45°
2cos^2(150°)-1=cos(2x150°)=cos300°=-cos60°=-1/2