Find an equation for the line with the given properties.

Question

Perpendicular to the line x=4; containing the point (1,3)

Answer 1

This is a simple problem, by design.  You don't need formulas, just reasoning.  The original line is vertical, its perpendicular will be horizontal, of the form y = some number.

 

If the perpendicular line contains (1,3), the equation must be y = 3.

Answer 2

The line x = 4 is a vertical line; any line perpendicular to that will be horizontal (& have slope 0).

 

If that horizontal line contains (1,3), then it must be the line y = 3.