Почему cos(3п/2-x) = -sinx а cos^2(3П/2-x)= sin^2x? Мы -sinx умножаем на -sinx?
Да, но проще заметить квадрат
![\cos\left(\dfrac{3\pi}{2}-x\right)=-\sin x\medskip\\\cos^2\left(\dfrac{3\pi}{2}-x\right)=\left[\cos\left(\dfrac{3\pi}{2}-x\right)\right]^2=\left[-\sin x\right]^2=\sin^2 x](https://tex.z-dn.net/?f=%5Ccos%5Cleft%28%5Cdfrac%7B3%5Cpi%7D%7B2%7D-x%5Cright%29%3D-%5Csin%20x%5Cmedskip%5C%5C%5Ccos%5E2%5Cleft%28%5Cdfrac%7B3%5Cpi%7D%7B2%7D-x%5Cright%29%3D%5Cleft%5B%5Ccos%5Cleft%28%5Cdfrac%7B3%5Cpi%7D%7B2%7D-x%5Cright%29%5Cright%5D%5E2%3D%5Cleft%5B-%5Csin%20x%5Cright%5D%5E2%3D%5Csin%5E2%20x "\cos\left(\dfrac{3\pi}{2}-x\right)=-\sin x\medskip\\\cos^2\left(\dfrac{3\pi}{2}-x\right)=\left[\cos\left(\dfrac{3\pi}{2}-x\right)\right]^2=\left[-\sin x\right]^2=\sin^2 x")