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Students need to rewrite a given trig espression in terms of one trig ratio only, Written as a scan solution and upload question, no randomisation.

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Using results for double angles and trig identities rewrite the expression \\[5\\cos 2\\theta+ \\cos^2\\theta-3\\] in terms of \\(\\sin\\theta\\) only.

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\\begin{align}5\\cos 2\\theta+ \\cos^2\\theta-3&=5(1-2\\sin^2\\theta)+\\cos^2\\theta-3\\quad\\text{using identity for }\\cos 2\\theta\\\\&=5(1-2\\sin^2\\theta)+(1-\\sin^2\\theta)-3\\quad\\text{using the Pythagorean identity}\\\\&=5-10\\sin^2\\theta+1-\\sin^2\\theta-3\\\\&=3-11\\sin^2\\theta\\quad\\text{as required}\\end{align}

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