Question

A+b+c=6,a^2+b^2+c^2=26 to ab+bc+ca ka man hoga

Answer 1

AB + BC + CA = 5

Step-by-step explanation:

Given,

A + B + C = 6 , and

$a^{2} + b^{2} + c^{2} = 26$

We know that,

$(A + B +C)^{2} = A^{2} + B^{2} + C^{2} + 2AB + 2BC + 2CA$

                     $= A^{2} + B^{2} + C^{2} + 2\times(AB + BC + CA)$

Putting the given values in above equations,

So, we get,

$(6)^{2} = 26 + 2\times(AB + BC + CA)$

$36 = 26 + 2\times(AB + BC + CA)$

$36 - 26 = 2\times(AB + BC + CA)$

$AB + BC + CA = \frac{10}{2}$

$AB + BC + CA = 5$