Question

How do you graph `r = 7`?

Answer 1

You get a circle of radius `7` and centered in the origin.

Explanation:

You can think of it in polar coordinates (where you are given a radius from the origin and an angle with the positive `x` semi-axis).
In this case your equation tells you that you need to plot all points at distance `7` from the origin at any possible angle...i.e., a circle with center in the origin and radius `7`!