Among the statements (S1) : If A(5, -1) and B(-2, 3) are two vertices of a triangle, whose orthocentre is (0, 0), then its third vertex is (-4, -7) and (S2) : If positive numbers 2a, b, c are three consecutive terms of an A.P., then the lines ax + by + c = 0 are concurrent at (2, -2),
- both are incorrect
- only (S2) is correct
- both are correct
- only (S1) is correct
Answer
(3) both are correct
Solution
(S1) Let C(h, k), orthocentre H(0, 0).
AH BC: 5(h + 2) - 1(k - 3) = 0 5h - k + 13 = 0
BH AC: -2(h - 5) + 3(k + 1) = 0 -2h + 3k + 13 = 0
h = -4, k = -7 ⇒ C(-4, -7) ⇒ (S1) is correct
(S2) 2a, b, c in A.P. 2b = 2a + c 2a - 2b + c = 0
(2, -2) satisfies ax + by + c = 0 for every such a, b, c ⇒ lines concurrent at (2, -2) ⇒ (S2) is correct
Both are correct.
Answer: (3)