Question

Тригонометрия. Сравните: sin 3p/5 и sin 4pi/5 sin 7pi/12 и 11pi/12 sin 8pi/9 и sin 7pi/9

Answer 1

$sin108^0=sin\frac{3\pi}{5}>sin\frac{4\pi}{5}=sin144^0\\\\sin105^0=sin\frac{7\pi}{12}>sin\frac{11\pi}{12}=sin165^0\\\\sin160^0=sin\frac{8\pi}{9}<sin\frac{7\pi}{9}=sin140^0$