Trig
posted by Ashley .
Verify the identity:
tanx(cos2x) = sin2x  tanx
Left Side = (sinx/cosx)(2cos^2 x 1)
=sinx(2cos^2 x  1)/cosx
Right Side = 2sinx cosx  sinx/cosx
=(2sinxcos^2 x  sinx)/cosx
=sinx(2cos^2 x 1)/cosx
= L.S.
Q.E.D.
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