Calculus help: describe set of (x, y, z) equidistant from

[mlane]

I need help describing a set of points (x,y,z) that is the same distance from the yz plane as it is to the x axis. I am not sure where to begin I have drawn some pictures to help visualize and I have referenced my book but I am still blank.
I need to come up with an equation and shape. I really don't know where to begin.

 

[stapel]

Have you tried using the Distance Formula, with the y,z-plane points being of the form (0, y, z) and the x-axis points being (x, 0, 0)?

Eliz.