Найдите значение выражения √300 cos^2 П/2 -√75

[latex] \sqrt{300}*cos^2 \frac{\pi}{2}- \sqrt{75}= 2\sqrt{75}*cos^2 \frac{\pi}{2}- \sqrt{75}=\\ \\ = 2 \sqrt{75}(cos^2 \frac{\pi}{2}- \frac{1}{2})= 2 \sqrt{75}(\frac{1+cos2* \frac{\pi}{2} }{2}- \frac{1}{2})= 2 \sqrt{75}(\frac{1+cos\pi }{2}- \frac{1}{2})= \\ \\ = 2 \sqrt{75}(\frac{1+cos\pi-1 }{2})= 2 \sqrt{75}*\frac{cos\pi }{2}= -2 \sqrt{75}*\frac{1 }{2}= -\sqrt{75}=-5 \sqrt{3} [/latex]