5.
jackson wants to paint a 3-foot border around the edge of the floor in his room. he drew this diagram to show how it should look.
what area of the floor will remain unpainted?

the first one

step-by-step explanation:

just id the test.

step-by-step explanation:

points a and b are equidistant from the desired line, so the line you find by using them will go through point r.

using points other than a and b will give the desired line only if they are equidistant from r. if they are randomly located, the perpendicular line you create will not necessarily go through point r, hence will not be a solution to the problem.