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Students need to prove a given trig identity, Written as a scan solution and upload question, no randomisation.

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Show that the identity \\[\\frac{\\sin 2\\theta\\sin\\theta}{2\\cos\\theta}=1-\\cos^2 \\theta\\] is true. Write your proof in your handwritten working.

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\\begin{align}LHS&=\\frac{\\sin 2\\theta\\sin\\theta}{2\\cos\\theta}\\\\&=\\frac{2\\sin^2 \\theta\\cos\\theta}{2\\cos\\theta}\\quad\\text{using double angle formula for }\\sin 2\\theta\\\\&=\\sin^2\\theta\\quad\\text{cancelling common factor of }2\\cos\\theta\\\\&=1-\\cos^2\\theta\\quad\\text{using the Pythagorean identity}\\\\&=RHS\\end{align}

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