6.Find the direction-cosines of a line which makes equal angles with the axes. How many such lines are there?
Let α be the angle which the line with all the axes, ∴ its direction-cosines are cos α, cos α, cos α required direction-cosines are These are four different groups of signs i.e., +, +, + +, -, + +, +, - +, -, - ∴ there are four distinct lines.
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7.
If a line has direction ratios 2, -1, -2, determine its direction cosines.
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8.
If a line has direction ratios 2, -1, -2, determine its direction cosines.
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9.If a line has the direction ratios – 18, 12, – 4. then what are its direction cosines?
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10.Find the direction ratios and the direction cosines of the lines joining the pairs of points: (–2, 1, 0), (3, 2, 1).