JEE Math Practice Question
An angle between the lines whose direction cosines are gien by the equations, $$l$$ + 3m + 5n = 0 and 5$$l$$m $$-$$ 2mn + 6n$$l$$ = 0, is :
- A.$${\cos ^{ - 1}}\left( {{1 \over 3}} \right)$$
- B.$${\cos ^{ - 1}}\left( {{1 \over 4}} \right)$$
- C.$${\cos ^{ - 1}}\left( {{1 \over 6}} \right)$$
- D.$${\cos ^{ - 1}}\left( {{1 \over 8}} \right)$$
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