Question

The equation of X-axis is.

• A. $\frac{X}{1}=\frac{Y}{0}=\frac{Z}{0}$
• B. $\frac{X}{0}=\frac{Y}{1}=\frac{Z}{1}$
• C. $\frac{X}{1}=\frac{Y}{1}=\frac{Z}{1}$
• D. None of these

Answer 1

The correct option is A $\frac{X}{1}=\frac{Y}{0}=\frac{Z}{0}$

The equation of a line with direction vector $\overrightarrow{d}=(l,m,n)$ that passes through the point $(x_1,y_1,z_1)$ is given by

$\frac{x-x_1}{l}=\frac{y-y_1}{m}=\frac{z-z_1}{n}$

For the $x$ axis, the line passes through the origin i.e. $(x_1,y_1,z_1)$ corresponds to $(0,0,0)$

Also, it is parallel to the x axis and perpendicular to y and z axes and so the direction ratio becomes $(1,0,0)$

$\Rightarrow$ The line equation can be written as $\frac{X}{1}=\frac{Y}{0}=\frac{Z}{0}$