Math, asked by vishnumanu421, 10 months ago

show that a (b^2+c^2)cos+b(c^2+a^2)cosB+ c(a^2+b^2)cosC=3abc​

Answers

Answered by spiderman2019
0

Answer:

Step-by-step explanation:

a(b²+c²)cosA+b(c²+a²)cosB+ c(a²+b²)cosC

=ab²CosA + ac²CosA + bc²CosB+ba²CosB+ ca²CosC+ cb²CosC

= ab(bCosA+aCosB) + bc(cCosB+bCosC)+ca(cCosA+aCosC)

= ab(c) + bc(a)+ca(b) (∵ Projection formula)

= 3abc​

= R.H.S

Hence proved

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