15 и 17 только спасибо)

Решите задачу:

$\sqrt{2}sin\frac{\pi}{8}*cos\frac{\pi}{8}=\frac{\sqrt{2}}{2}(2sin\frac{\pi}{8}cos\frac{\pi}{8})=\frac{\sqrt{2}}{2}*sin(2*\frac{\pi}{8})=\frac{\sqrt{2}}{2}*sin\frac{\pi}{4}=\\=\frac{\sqrt{2}}{2}*\frac{\sqrt{2}}{2}=\frac{1}{2}$

$\sqrt{75}-\sqrt{300}sin^2\frac{13\pi}{12}=\sqrt{75}(1-2sin^2\frac{13\pi}{12})=\sqrt{75}*cos(2*\frac{13\pi}{12})=\\=\sqrt{75}*cos\frac{13\pi}{6}=\sqrt{75}*cos\frac{\pi}{6}=\sqrt{75}*\frac{\sqrt{3}}{2}=\frac{15}{2}$