Vector-Algebra Question 422

Question: If $ \overset{\to }{\mathop{c}}, $ is the unit vector perpendicular to both the vectors $ \overset{\to }{\mathop{a}}, $ and $ \overset{\to }{\mathop{b}}, $ , then what is another unit vector perpendicular to both the vectors $ \overset{\to }{\mathop{a}}, $ and $ \overset{\to }{\mathop{b}},? $

Options:

A) $ \overset{\to }{\mathop{c}},\times \overset{\to }{\mathop{a}}, $

B) $ \overset{\to }{\mathop{c}},\times \overset{\to }{\mathop{b}}, $

C) $ -\frac{( \overset{\to }{\mathop{a}},\times \overset{\to }{\mathop{b}}, )}{| \overset{\to }{\mathop{a}},\times \overset{\to }{\mathop{b}}, |} $

D) $ \frac{( \overset{\to }{\mathop{a}},\times \overset{\to }{\mathop{b}}, )}{| \overset{\to }{\mathop{a}},\times \overset{\to }{\mathop{b}}, |} $

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Answer:

Correct Answer: D

Solution:

  • [d] Let $ \overset{\to }{\mathop{c}}, $ is the unit vector perpendicular to both the vectors $ \overset{\to }{\mathop{a}}, $ and $ \overset{\to }{\mathop{b}}, $ . So, A unit vector which is perpendicular to both the vectors $ \overset{\to }{\mathop{a}}, $ and $ \overset{\to }{\mathop{b}}, $ is $ \frac{( \overset{\to }{\mathop{a}},\times \overset{\to }{\mathop{b}}, )}{| \overset{\to }{\mathop{a}},\times \overset{\to }{\mathop{b}}, |} $