If a, b, c are the direction ratios of the line and l, m, n are the di – McqOptions

MCQOPTIONS

1.	If a, b, c are the direction ratios of the line and l, m, n are the direction cosines of the line, then which of the following is incorrect?
A.	( frac{l}{a}= frac{m}{b}= frac{n}{c}=k )
B.	l<sup>2</sup>+m<sup>2</sup>+n<sup>2</sup>=1
C.	k=&pm; ( frac{1}{ sqrt{(a^2+b^2+c^2)}} )
D.	l<sup>2</sup>-m<sup>2</sup>=n<sup>2</sup>-1
Answer» E.

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