证明：(cosx)^8-(sinx)^8-cos2x=-1/4sinaxsin2x如题

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证明：(cosx)^8-(sinx)^8-cos2x=-1/4sinaxsin2x如题证明：(cosx)^8-(sinx)^8-cos2x=-1/4sinaxsin2x如题证明：(cosx)^8-(s

证明：(cosx)^8-(sinx)^8-cos2x=-1/4sinaxsin2x如题
证明：(cosx)^8-(sinx)^8-cos2x=-1/4sinaxsin2x
如题

证明：(cosx)^8-(sinx)^8-cos2x=-1/4sinaxsin2x如题
证明：(cosx)^8-(sinx)^8-cos2x
=[(cosx)^4+(sinx)^4][(cosx)^4-(sinx)^4]-cos2x
=[(cosx)^4+(sinx)^4][(cosx)^2+(sinx)^2][(cosx)^2-(sinx)^2]-cos2x
=[(cosx)^4+(sinx)^4]cos2x-cos2x
=[(cosx)^4+(sinx)^4-1]cos2x
={[(1+cos2x)/2]^2+[(1-cos2x)/2]^2-1}cos2x
=1/4[1+2cos2x+(cos2x)^2+1-2cos2x+(cos2x)^2-4]cos2x
=1/4*2[(cos2x)^2-1]cos2x
=-1/4*2(sin2x)^2cos2x
=-1/4sin4xsin2x
打得累死了.可怜可怜~~~给点分吧.

证明：(cosx)^8-(sinx)^8-cos2x=-1/4sina????xsin2x

证明 (sinx)' = cosx；用数学归纳法证明下列等式cosx/2*cosx/4*cosx/8…cosx/2^n =sinx/（2^n*sinx/(2^n)）证明:2(cosx-sinx)/1+sinx+cosx=cosx/1+sinx-sinx/1+cosx 证明:【2(cosx-sinx)】/(1+sinx+cosx)=cosx/(1+sinx) -sinx/(1+cosx) 证明:2(cosx-sinx)/1+sinx+cosx=cosx/1+sinx-sinx/1+cosx 证明cosX导数为-sinX 证明sinx*cosx=sin2x cscX+cosX=sinx/(1-cosx)证明, 证明：(cosx)^8-(sinx)^8-cos2x=-1/4sinaxsin2x如题证明2(cosx-sinx)/(1+sinx+cosx)=cosx/(1+sinx)-sinx/(1+cos) 证明cosx/1-sinx=1+sinx/cosx 证明1+sin2x/sinx+cosx=sinx+cosx(详细答案) 怎么证明cos2x/1-sin2x = cosx+sinx/cosx-sinx 1-2sinx*cosx/(cosx+sinx)(cosx-sinx)=1-tanx/(1+tanx)怎么证明证明2sinxcosx/(sinx+cosx-1)(sinx-cosx+1)=1+cosx/sinx? 利用三角函数定义来证明(cosx-sinx+1)/(cosx+sinx+1)=(1-sinx)/cosx, 证明(1+sinx + cosx)/(1+sinx - cosx)=(1+cosx+cotx+cscx)/(1+sinx) 证明2SINXCOSX/(SINX+COSX-1)(SINX-COSX+1)=(I+COSX)/SINX