Question

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

Answer 1

$5sin(frac{13pi}{12})cos(frac{13pi}{12}) = frac{5}{2}cdot2sin(frac{13pi}{12})cos(frac{13pi}{12}) = frac{5}{2}sin(2cdotfrac{13pi}{12})=frac{5}{2}sin(frac{13pi}{6})=frac{5}{2}sin(2pi+frac{pi}{6})$$=frac{5}{2}sin(frac{pi}{6})=frac{5}{2}cdotfrac{1}{2}=frac{5}{4}$