Solve sin3x + sinx/cosx + cos3x= tan2x

allhvasstH 2020-11-05 Answered
Solve sin3x+sinxcosx+cos3x=tan2x
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Nichole Watt
Answered 2020-11-06 Author has 100 answers
sinA+sinB=2sin(A+B2)cos(AB2),
cosA+cosB=2cos(A+B2)cos(AB2).
If A=3x and B=x, sin3x+sinx=2sin2xcosx,cos3x+cosx=2cos2xcosx.
Therefore sin3x+sinxcosx+cos3x=2sin2xcosx2cos2xcosx=tan2x
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