SOLUTION: Prove : tanx + tanxcos2x=sin2x

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Question 1189411: Prove : tanx + tanxcos2x=sin2x
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

tan%28x%29+%2B+tan%28x%29cos%282x%29=sin%282x%29
manipulate left side
tan%28x%29%281+%2B+cos%282x%29%29+...........use Double-Angle Identities cos%282x%29=2cos+%5E2%28x%29-1 and identity tan%28x%29=sin%28x%29%2Fcos%28x%29
=%28sin%28x%29%2Fcos%28x%29%29%281%2B2cos+%5E2%28x%29-1%29+
=%28sin%28x%29%2Fcos%28x%29%29%282cos+%5E2%28x%29%29+..........simplify
=2sin%28x%29cos+%28x%29....................use Double-Angle Identities sin%282x%29=+2sin%28x%29cos+%28x%29
=sin%282x%29-> proven