1.

A line with DCs proportional to 2, 1, 2 meets each of the lines x = y + a = z and x + a = 2y = 2z. The coordinates of each of the points of intersection are(a)  (3a, 2a, 3a), (a, a, 2a)(b)  (3a, 2a, 3a), (a, a, a)(c)  (3a, 3a, 3a), (a, a, a)(d)  (2a, 3a, 3a), (2a, a, a)

Answer»

Correct option is (b) (3a, 2a, 3a), (a, a, a)

Explanation :

The given line L1 is

x/1 = (y + a)/1 = z/1

P is a point on L1. Therefore

P = (t, -a + t, t) ...(1)

and the given line L2 is

(x + a)/2 = y/1 = z/1

Q is a point on L2. Therefore

Q = (-a + 2s,s,s) ...(2)

From Eqs. (1) and (2), the DRs of vector PQ are 

(2s - a - t,s - t + a,s - t) 

Therefore, by hypothesis, we have

(2s - a - t)/2 = (s - t + a)/1 = (s - t)2

Hence

(2s - a - t)/2 = (s - t + a)/1

t = 3a

(s - t + a)/1 = (s - t)/2 

s - t = - 2a

s = a (∵ t = 3a)

Therefore, P = (3a, 2a, 3a) and Q = (a, a, a)



Discussion

No Comment Found

Related InterviewSolutions