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Question
Find the equation of a line parallel to x-axis and passing through the origin.
Solution
The direction cosines of the x-axis are 1, 0, 0.
∴ The direction cosines of the line parallel to the x-axis will also be 1, 0, 0.
Hence, the equation of the line through the origin with direction cosines 1, 0, 0 is.
⇒ `(x - 0)/1 = (y - 0)/0 = (z - 0)/0`
⇒ `x/1 = y/0 = z/0`
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