(i)[1]
Show that, after expansion, $\cos^4 x = 1 - 2\sin^2 x + \sin^4 x$.
(ii)[5]
Hence, or otherwise, solve the equation $8\sin^4 x + \cos^4 x = 2\cos^2 x$ for $0^\circ \leq x \leq 360^\circ$.
Mathematics 9709 · AS & A Level · Trigonometry
Mathematics 9709 · AS & A Level · Trigonometry
Show that, after expansion, $\cos^4 x = 1 - 2\sin^2 x + \sin^4 x$.
Hence, or otherwise, solve the equation $8\sin^4 x + \cos^4 x = 2\cos^2 x$ for $0^\circ \leq x \leq 360^\circ$.