BITSAT 2014 Paper

If the given points be A (2, 3, 4) and B (6, 7, 8), then their mid-point N(4, 5, 6) must lie on the plane. The direction ratios of AB are 4, 4, 4, i.e. 1, 1, 1.

∴ The required plane passes through N (4, 5, 6) and is normal to AB. Thus its equation is
1(x - 4) +1(y - 5) +1(z - 6) = 0 ⇒ x + y + z = 15