Question

Вычислите: sin5p/24*sinp/24-cosp/24*cos5p/24

Answer 1

$Sin\frac{5\pi }{24}*Sin\frac{\pi }{24}-Cos\frac{\pi }{24}*Cos\frac{5\pi }{24}=-Cos(\frac{5\pi }{24}+\frac{\pi }{24})=-Cos\frac{6\pi }{24}=-Cos\frac{\pi }{4}=-\frac{\sqrt{2}}{2}$