estern

Verified answer

3*sin(13pi/12)*cos(13pi/12) = ?

sin(13pi/12) = sin(pi - 13pi/12) = sin(-pi/12) = -sin(pi/12)
cos(13pi/12) = -cos(pi - 13pi/12) = -cos(-pi/12) = -cos(pi/12)

3*sin(13pi/12)*cos(13pi/12) = 3*sin(pi/12)*cos(pi/12) = 3/2*sin(pi/6) = 3/4 = 0.75