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प्रश्न
Which of the following represents direction cosines of the line :
(a)`0,1/sqrt2,1/2`
(b)`0,-sqrt3/2,1/sqrt2`
(c)`0,sqrt3/2,1/2`
(d)`1/2,1/2,1/2`
उत्तर
Ans. (C)
`l^2+m^2+n^2`
`=(0)^2+(sqrt3/2)^2+(1/2)^2`
`=3/4+1/4=1`
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