Question

Найдите значение выражения 5sin 13pi/12*cos 13pi/12

Answer 1

$5Sin\frac{13\pi} {12}*Cos \frac{13\pi} {12}=5Sin( \pi+ \frac{\pi} {12})*Cos( \pi+ \frac{\pi} {12})=5*(-Sin \frac{\pi} {12})*(-Cos \frac{\pi} {12})=2,5*2Sin \frac{\pi} {12}Cos \frac{\pi} {12} =2,5Sin\frac{\pi} {6}=2,5* \frac{1}{2}=1,25$