tan(X+45度）=1/3,(sinX-cosX)^2/cos2x?

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tan(X+45度）=1/3,(sinX-cosX)^2/cos2x?
A.3
B.-3
C.2
D.-2

(sinx-cosx)^2/cos2x
=(sinx-cosx)/(cos^2x-sin^2x)
=(sinx-cosx)/(sinx+cosx)
=(tanx-1)/(1+tanx)
=tan（x-45°）=1/3

tan(X+45度）=1/3,(sinX-cosX)^2/cos2x? cos3x+2cosx=0 .sinx tan x/2 =1 .sinx - cosx = san2x -cos2x 求证:tan(3x/2)-tan(x/2)=(2sinx)/(cosx+cos2x) 证明:tan[3x/2]-tan[x/2]=2sinx/[cosx+cos2x] 证明：tan[3x/2]-tan[x/2]=2sinx/[cosx+cos2x] 证明tan(3x/2)-tan(x/2)=(2sinx)/(cosx+cos2x) 求证:tan(3x/2)-tan(x/2)=2sinx/(cosx+cos2x) 已知2sin2x-cos2x+sinxcosx-6sinx+3cosx=0，求2cosx(sinx+cosx)1+tan 求证 sin^2x/(sinx-cosx)-(sinx+cosx)/tan^2 x-1=sinx+cosx 若cos2X/sin（X—45度）=根号2/2 则cosX+sinX? 三角函数：x属于（0.90度）,cosX+sinX=-1/3,则cos2X=? 证明：tan（x／2）=sinx／1+cosx