Answer:
ab + bc + ca = 47
Explanation:
Using the algebraic identity
(a + b + c) = a² + b² + c² + 2(ab + bc + ca) , then
12² = 50 + 2(ab + bc + ca)
144 = 50 + 2(ab + bc + ca) ← subtract 50 from both sides
94 = 2(ab + bc + ca) ← divide both sides by 2
47 = ab + bc + ca