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Prove that the three lines from the orig...

Prove that the three lines from the origin O, with direction cosines `l_1,m_1,n_1; l_2,m_2,n_2;l_3,m_3,n_3` are coplaner if `|[l_1,m_1,n_1],[l_2,m_2,n_2],[l_3,m_3,n_3]|=0`

A

`-[{:(l_1,n_1,m_1),(l_2,n_2,m_2),(l_3,n_3,m_3):}]`

B

`[{:(l_1,n_1,m_1),(l_2,n_2,m_2),(l_3,n_3,m_3):}]`

C

`l_1l_2l_3+m_1m_2m_3+n_1n_2n_3=0`

D

None of these

Text Solution

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The correct Answer is:
A
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