sin(a-b)cosb+cos(a-b)sinb=?
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sin(a-b)cosb+cos(a-b)sinb=?sin(a-b)cosb+cos(a-b)sinb=?sin(a-b)cosb+cos(a-b)sinb=?sin(a-b)cosb+cos(a-
sin(a-b)cosb+cos(a-b)sinb=?
sin(a-b)cosb+cos(a-b)sinb=?
sin(a-b)cosb+cos(a-b)sinb=?
sin(a-b)cosb+cos(a-b)sinb
=sin(a-b+b)
=sina
sin(a-b)cosb+cos(a-b)sinb=?
cos(a-b)cosb-sin(a-b)sinb
cos(a-b)cosb-sin(a-b)sinb等于什么
化简cos(a+b)cosb+sin(a+b)sinb
化简:cos(A-B)cosB-sin(A-B)sinB
cosb=cos[(a+b)-a]=cos(a+b)cosa+sin(a+b)sina
[sin(2a+b)cosb+cos(2a+b)sinb]/[cos(2a+b)cosb]=[sin(2a+2b)]/[cos(2a+b)cosb]是怎么来的,看不懂
sin(a-b)cosb+cos(b-a)sinb=cos(b-a)怎么变形,为什么?
证明下列恒等式:sin(a+b)*cos(a-b)=sina*cosa+sinb*cosb
化简cos(a-b)cosb-sin(a-b)cosb的 结果是
sin(2a+b)cosb+cos(2a+b)sinb怎么等到sin(2a+2b)的呢
sin²a+sin²b-sina²sin²b+cos²cosb=1
sin(a+b)cosb-cos(a+b)sinb=0,则sin(a+2b)+sin(a-2b)等于?我算出为0!
sin(a+b)cosb-cos(a+b)sinb=0 则sin(a+2b)+sin(a-2b)=
证明cosA+cosB+cosC=1+4sin(A/2)sin(B/2)sin(C/2)证明:cosA+cosB+cosC=1+4sin(A/2)sin(B/2)sin(C/2)尽量详细一点选做cosA+cosB+cosC=1+4sin(A/2)sin(B/2)sin(C/2) cos(180-B-C)+cosB+cosC=1+2sin(A/2)[2sin(B/2)sin(C/2)] cos(180-B-C)+cosB+cosC
cos a+cosb=-1/3 sin a+sin b=1/2 求cos(a+b)
为什么sinb=sin(a+b-b)=sin(a+b)cosb+cos(a+b)sinb,这是公式吗?
若a,b为两个锐角,则( ) ,A,cos (a+b)>cosa +cosb B,cos(a+b)<cosa +cosbC,cos (a+b)>sina +sinb D,cos (a+b)<sina +sin b 【说明原因】