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Hi! Can someone help me solve the equation sin3x+sinx+cosx=0 on [0,2pi)?

2007-10-21 18:11:55 · 1 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics

1 answers

write sin3x+sinx as a product
sin3x+sinx=2sin2xcosx
2sin2xcosx+cosx=0
cosx(2sin2x+1)=0

cosx=0 x=90,270
sin2x=-1/2

2x=-30
x=-15

2x=180+30=210
x=105

2007-10-21 18:19:52 · answer #1 · answered by iyiogrenci 6 · 1⤊ 0⤋

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