Question

найдите значение выражения cos 3п/4​

Answer 1

cos(3п/4)=cos135°=-sqrt(2)/2

Answer 2

$cos\frac{3\pi}{4}=cos(\frac{\pi}{2}+\frac{\pi}{4}) =-sin\frac{\pi}{4}=-\frac{\sqrt{2}}{2}$

$cos\frac{3\pi}{4}=-\frac{\sqrt{2}}{2}$ ≈ -0,7