1.若(z-x)2-4(x-y)(y-z)=0.求证:x,y,z成等差数列..ps:这里的2是平方..2.在三角形ABC中,若BC=a,CA=b,AB=c,且sin2A,sin2B,sin2C成等差数列,求证:cosA/a,cosB/b,cosC/c也成等差数列..ps:这里的2也是平方..3.已知一等差数
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1.若(z-x)2-4(x-y)(y-z)=0.求证:x,y,z成等差数列..
ps:这里的2是平方..
2.在三角形ABC中,若BC=a,CA=b,AB=c,且sin2A,sin2B,sin2C成等差数列,求证:cosA/a,cosB/b,cosC/c也成等差数列..
ps:这里的2也是平方..
3.已知一等差数列的第p项是M,第q项是N,第r项是K.求证:M(q-r)+N(r-p)+K(p-q)=0...
随便解决掉一题也可以的...我实在不会做....
3.设公差为d. d=(ap-aq)/(p-q)=(m-n)/(p-q)
=(aq-ar)/(q-r) =(n-k)/(q-r)
=(ar-ap)/(r-p)=(k-m)/(r-p)
注;pqr均为下标
M(q-r)+N(r-p)+K(p-q)=m(n-k)/d+n(k-m)/d+k(m-n)/d=0
打字好累啊,一句话说不清啊!有事再问我吧!先做这道简单的吧!
若x,y,z成等差数列,则(z-x)^2-4(x-y)(y-z)=
若x,y,z成等差数列,则(z-x)^2-4(x-y)(y-x)=
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