You are going to go on a walk from your house to the store, then to your friend's house, and finally back home. There are 10 ways to get from your house to the store, 3 ways to get from the store to your friend's house, and 4 ways to get from your friend's house back to your house. How many possible routes can you take on your walk?​

the third picture

step-by-step explanation:

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.