JEE Math Practice Question
The angle between the straight lines, whose direction cosines are given by the equations 2l + 2m $$-$$ n = 0 and mn + nl + lm = 0, is :
- A.$${\pi \over 2}$$
- B.$$\pi - {\cos ^{ - 1}}\left( {{4 \over 9}} \right)$$
- C.$${\cos ^{ - 1}}\left( {{8 \over 9}} \right)$$
- D.$${\pi \over 3}$$
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