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Centroid of the tetrahedron OABC, where A ≡ (a, 2, 3) , B ≡ (1, b, 2) , C ≡ (2, 1, c) and O is the origin is (1, 2, 3). The value of a2 + b2 + c2 is equal to : |
75 80 121 None of these |
75 |
We have 4 = a + 1 + 2 + 0, ⇒ a = 1, 8 = 2 + b + 1 + 0 ⇒ b = 5, 12 = 3 + 2 + c + 0 ⇒ c = 7, ∴ a2 + b2 + c2 = 1 + 25 + 49 = 75 |
