Question

4(cos^2 п/8-sin^2п/8)-6sin п/4

Answer 1

4(cos² п/8-sin² п/8)-6sin п/4=4cos π/4-6sin π/4=
=4*$\frac{ \sqrt{2} }{2}-6* \frac{ \sqrt{2} }{2}$=-2*$\frac{ \sqrt{2} }{2}$=-√2