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Two lines with directino cosines lt l(1)...

Two lines with directino cosines `lt l_(1), m_(1), n_(1) gt and lt l_(2), m_(2), n_(2) gt` are at right angles if

A

`l_(1) = l_(2), m_(1) = m_(2), n_(1) = n_(2)`

B

`(l_(1))/(l_(2)) = (m_(1))/(m_(2)) = (n_(1))/(n_(2))`

C

`l_(1)l_(2) + m_(1)m_(2) + n_(1) n_(2) = 0 `

D

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

Text Solution

Verified by Experts

The correct Answer is:
C
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