if cos A is equal to root 3 by 2 find cos 2a
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cosA=√(3/2)
square each side
cos^2A=3/2
we know that
cos2A=cos^2A-sin^2A
cos2A=2cos^2A-1
cos2A=2×3/2-1
cos2A=3-1
cos2A=2
square each side
cos^2A=3/2
we know that
cos2A=cos^2A-sin^2A
cos2A=2cos^2A-1
cos2A=2×3/2-1
cos2A=3-1
cos2A=2
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