Question

find the value of a for which the vector 3 ICAP + 3 j cap + 9 k cap and ICAP + a j cap + 3 k cap Are parallel
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Answer 1

These two vectors (V1) and (V2) are parallel when their direction ratios must be proportionate.

Here, (V1) = 3i + 3j + 9k and (V2) = i + aj + 3k.

So, for (V1) and (V2) being parallel:

(3 / 1) = (3 / a) = (9 / 3)

So, a = 1...

Hope it helps u....