1+2sin2x+2(cosx)平方
=(sinx)平方+4sinxcosx+3(cosx)平方
=(sinx+cosx)(sinx+3cosx)=0
sinx+cosx=0或sinx+3cosx=0
tanx=-1或tanx=-3
x=-π/4或3π/4或arctan(-3)或π+arctan(-3)
1+2sin2x+2(cosx)平方
=(sinx)平方+4sinxcosx+3(cosx)平方
=(sinx+cosx)(sinx+3cosx)=0
sinx+cosx=0或sinx+3cosx=0
tanx=-1或tanx=-3
x=-π/4或3π/4或arctan(-3)或π+arctan(-3)