Question

Find the value of k if one line is perpendicular to another line

Answer 1

Sol: If straight lines are perpendicular to each other then product of slopes equal to -1. Given straight lines x/3 + y/4 = 7 and 3x + ky = 11 ⇒ 4x + 3y = 84 and 3x + ky = 11 If straight line ax + by + c = 0 then slope m = - a / b. Now m1 = -4 / 3 and m2 = -3 / k. ⇒ m1m2 = -1 ⇒ (-4 / 3)(-3 / k) = -1 ⇒ 4 / k = -1 ∴ k = -4