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If lt l(1), m(1), n(1)gt and lt l(2), m(...

If `lt l_(1), m_(1), n_(1)gt and lt l_(2), m_(2), n_(2) gt` be the direction cosines of two lines `L_(1) and L_(2)` respectively. If the angle between them is `theta`, the `costheta=?`

A

`l_(1)l_(2)+m_(1)m_(2)+n_(1)n_(2)`

B

`l_(1)m_(1)+m_(1)n_(1)+n_(1)l_(1)`

C

`l_(2)m_(2)+m_(2)n_(2)+n_(2)l_(2)`

D

`m_(1)l_(2)+l_(2)m_(2)+n_(1)m_(2)`

Text Solution

Verified by Experts

The correct Answer is:
A
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