If the angle between the lines with direction ratios (1,0 , pm cos alpha) is 60^(circ) , then what is the value

### Question Asked by a Student from EXXAMM.com Team

Q 2359378214.     If the angle between the lines with direction ratios

(1,0 , pm cos alpha) is 60^(circ) , then what is the value of alpha?
NDA 2008 Paper 1
A

cos^(-1) (1/sqrt(2) )

B

cos^(-1) (1/sqrt(3) )

C

cos^(-1) (1/3 )

D

cos^(-1) (1/2 )

#### HINT

(Provided By a Student and Checked/Corrected by EXXAMM.com Team)

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