Question

Решить тригонометрию!
2cos36*sin18

Answer 1

$2*cos36*sin18=2*cos36*cos72= \frac{2*cos36*cos72*sin36}{sin36} = \frac{sin72*cos72}{sin36}$$\frac{ \frac{1}{2} sin144}{sin36} = \frac{ \frac{1}{2}sin36 }{sin36} =$$\frac{1}{2}$