Question

cos^2 x/2 - sin^2 x/2 =-1 помогите

Answer 1

$Cos^{2}\frac{x}{2}-Sin^{2}\frac{x}{2}=-1\\\\Cosx=-1\\\\x=\pi+2\pi n,n$∈z

Answer 2

${ {{cos^2\frac{x}{2}-sin^2\frac{x}{2}=-1} \atop {cos^2\frac{x}{2}+sin^2\frac{x}{2}=1}} \right. +\\2cos^2\frac{x}{2}=0\\cos^2\frac{x}{2}=0\\ cos\frac{x}{2}=0\\ \frac{x}{2}=\frac{\pi}{2}+\pi n, n \in Z\\x=\pi +2\pi n,n \in Z$

Ответ: $\pi+2\pi n, n \in Z$