Question

Find k for the given plane x + 2y + kz + 2 = 0 and directional ratios of a line (8, 3, 2), if they are parallel to each other.

(a) 21

(b) -17

(c) 12

(d) -7

This question was addressed to me in homework.

My question is from Three Dimensional Geometry in portion Three Dimensional Geometry of Mathematics – Class 12

Answer 1

The correct answer is (d) -7

For explanation: The condition for a plane and a line are parallel to each other is a1a + b1b + c1c = 0.

8(1) + 3(2) + 2(k) = 0

2(k) = -14

k = -7