Question

if a square + b square + 3 square equals to 109 and a + b + c equals to23 then find the value of ab+bc+ca​

Answer 1

a² +b²+c²=109

a+b+c=23

ab+bc+ca=?

(a+b+c) whole square =a²+b²+c²+2ab+2bc+2ca

23 whole square=109+2(ab+bc+ca)

529=109+2(ab+bc+ca)

529-109=2(ab+bc+ca)

420=2(ab+bc+ca)

420/2=ab+bc+ca

210=ab+bc+ca

∴ANSWER=

ab+bc+ca=210