Question

Обчисліть 4sin$frac{ pi }{24}$*sin$frac{5 pi }{24}$

Answer 1

$cosfrac{2pi }{3}=cos(pi -frac{pi}{3})=-cosfrac{pi}{3}=-frac{1}{2}\\4sinfrac{pi}{24}sinfrac{5pi }{24}=4cdot frac{1}{2}(cosfrac{4pi }{24}-cosfrac{6pi }{24})=2(cosfrac{pi}{6}-cosfrac{pi}{4})=\\=2(frac{sqrt3}{2}-frac{sqrt2}{2})=sqrt3-sqrt2$

Answer 2

спасибо