Question

if a^2+b^2+c^2=90 and ab+bc+ca=5 find the value of a+b+c

Answer 1

Answer:

Given a²+b²+c²=90 and

ab+bc+ca=5 .....(i)

multiply 2 on both side of the equation we get

2ab+2bc+2ca=10

we know that

(a+b+c)²=a²+b²+c²+2ab+2bc+2ca

=90+10=100

So a+b+c = 10