Question

(cos п/8 - sin п/8) во 2 степени

Answer 1

$(\cos \frac{\pi}{8}-\sin\frac{\pi}{8})^2=\cos^2\frac{\pi}{8}+\sin^2\frac{\pi}{8}-2\sin\frac{\pi}{8}\cos\frac{\pi}{8}=1-\sin(2\cdot \frac{\pi}{8})=\\ \\ \\ =1-\sin\frac{\pi}{4}=1-\frac{1}{\sqrt{2}}$

Answer 2

(cosπ/8 - sinπ/8)²= cos²π/8 - 2*(cosπ/8)*(sinπ/8)+sin²π/8=1-sinπ/4=1-0.5√2