If a + b + c = 10 and a^2 + b^2 + c^2 = 38
then ab + bc + ca =
31
62
0
100
If a+b+c = 10 and a2+b2+c2=38; find ab+bc+ca
If a+b+c=10 and a2+b2+c2=36, then ab+bc+ca= .......... .