Trigonometrie clasa a 9-a

Răspuns:
Explicație pas cu pas:
[tex]\texttt{Se foloseste fomula }\boxed{\sin2x=2\cdot\cos x\cdot\sin x}\\\\\dfrac{\sin 8x}{8\sin x}=\dfrac{2\sin 4x\cdot\cos 4x}{8\sin x}=\dfrac{2\cdot 2\cdot\sin2x\cdot\cos2x\cdot\cos4x}{8\sin x}=\\\\=\dfrac{4\cdot2\cdot\sin x\cdot\cos x\cdot\cos 2x\cdot\cos 4x}{8\cdot\sin x}=\dfrac{8\cos x\cdot\cos 2x\cdot\cos 4x}{8}=\\=\boxed{\cos x\cdot\cos 2x\cdot\cos 4x}[/tex]