If a = 345, b = 344, c = 343, then
find a2 + b2 + c2 - ab - bc - ca.
Answer & explanation
Correct answer: option 2
a2 + b2 + c2 - ab - bc - ca = \(\frac{1}{2}\) [(a - b)2 + (b - c)2 + (c - a)2]
= \(\frac{1}{2}\) [(345 - 344)2 + (344 - 343)2 + (343 - 345)2]
= \(\frac{1}{2}\) [1 + 1 + 4] = 3