已知tanx=3,则4sin'2x-3sinxco - 知识问答

已知tanx=3,则4sin'2x-3sinxcosx-5cos'2x=?

1个回答

4sin'2x-3sinxcosx-5cos'2x
=8sinxcosx-3sinxcosx-10(1+cos^2 x)
=5tanx (1/1+tan^2 x)-10(1+1/(1+tan^2 x))
=5*3 /(1+9) -10 (1+1/10)
=1.5-11
=-9.5

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