Show that: sin(45° + A) sin(45º - A) =COS2A÷2
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Step-by-step explanation:
sin(45+A)sin(45-A)
=sin²45cos²A-cos²45sin²A
=1/2cos²A-1/2sin²A
=1/2(cos²A-sin²A)
=1/2(cos2A)
=cos2A/2
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