Question

if a+b+c=12 and a square+b square+c square=66 find the value of ab+bc+ca pls done it on paper

Answer 1

he friend hope this helps us

Answer 2

using
(a + b + c)² =

a² + b² + c² + ab + bc + ca

Given,
a + b + c = 12
Squaring both the sides,
(a + b + c)² = (12)²

=> a² + b² + c² + ab + bc + ca = 144

Substituting the value of a² + b² + c² we have

66 + 2ab + 2bc + 2ca = 144

=> 2ab + 2bc + 2ca = 144 - 66
=> 2ab + 2bc + 2ca = 78

Taking 2 common,
2(ab + bc + ca) = 78
=> ab + bc + ca = 78/2
=> ab + bc + ca = 39
Hope it helps dear friend ☺️✌️✌️