Answer:
Step-by-step explanation:
cos 2α=1-2 sin² α
[tex]sin \alpha =\sqrt{\frac{1-cos2\alpha }{2} } \\put~ \alpha =\frac{\pi }{8} \\2\alpha =\frac{\pi }{4} \\cos 2\alpha =cos \frac{\pi }{4}=\frac{1}{\sqrt{2} } \\\\sin(\pi/8)=\sqrt{\frac{1-\frac{1}{\sqrt{2} } }{2}} =\sqrt{\frac{\sqrt{2}-1 }{2\sqrt{2} }[/tex]
6 sin 3 \theta+6 sin \theta
[tex]6 sin 3 \alpha +6 sin\alpha =6(sin 3\alpha +sin \alpha )\\=6 *2sin \frac{3\alpha+\alpha }{2} cos \frac{3\alpha-\alpha }{2} \\=12 sin 2\alpha cos \alpha[/tex]
please change α to \theta
