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Grade 12th passTrigonometry

cos2A+cos2B+cos2C=cosB×cosC+cosC×cosA+cosA×cosB then prove that the trangle are equilateral

Profile image of manoj kumar
7 Years agoGrade 12th pass
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1 Answer

Profile image of Aditya Gupta
7 Years ago
let cosA=x, cosB=y, cosC=z
the given equation becomes 
(x-y)^2+(y-z)^2+(z-x)^2=0
so cosA=cosB=cosC implying that A=B=C, therefore the triangle is equilateral

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