3sin10*sin50*sin70 помогите решить

3sin (10) * 0.5 * (cos (50-70) - cos (50+70)) = 1.5*sin (10) * (cos (20) - cos (120)) = 1.5*sin (10) * cos (20) - 1.5*sin (10) * cos (180 - 60) = 1.5*0.5 * (sin (10-20) + sin (10+20)) + 1.5*sin (10) * cos (60) = - 0.75*sin (10) + 0.75*sin (30) + 0.75*sin (10) = 0.75*0.5 = (3/4) * (1/2) = 3/8 = 0.375