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In a DeltaA B C , prove the following :...

In a ` DeltaA B C ,` prove the following : `c\ (acosB-bcosA)=a^2-b^2dot`

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Consider
`c(a cos B-b cos A)=c a cos B-c b cos A`
`=c a(a^2+c^2-b^2)/(2 a c)-c b(b^2+c^2-a^2)/(2 b c)`
`=(a^2+c^2-b^2-b^2-c^2+a^2)/2`
`=(2(a^2-b^2))/2 `
`=a^2-b^2`
Hence proved.
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