sin3x-sin2x+sinx=0答案是x=kπ/2或x=2kπ+π/3或x=2kπ-π/3,

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sin3x-sin2x+sinx=0答案是x=kπ/2或x=2kπ+π/3或x=2kπ-π/3,

sin3x-sin2x+sinx=0答案是x=kπ/2或x=2kπ+π/3或x=2kπ-π/3,
sin3x-sin2x+sinx=0
答案是x=kπ/2或x=2kπ+π/3或x=2kπ-π/3,

sin3x-sin2x+sinx=0答案是x=kπ/2或x=2kπ+π/3或x=2kπ-π/3,
sin3x-sin2x+sinx=sin(x+2x)-sin2x+sinx=sinxcos2x+sin2xcosx-sin2x+sinx
=sinx(1+cos2x)+sin2x(cosx-1)=sinx*2cos^2x+2sinxcosx(cosx-1)
=2sinxcosx(cosx+cosx-1)=sin2x(2cosx-1)
当sin2x=0时,2x=kπ(k∈Z),此时x=kπ/2;
当2cosx=1时,cosx=1/2,此时x=2kπ+π/3或x=2kπ-π/3(k∈Z)