Yana, Josh, and Katrina are standing at the vertices of a righi triangle as they
throw a frisbee. Yana and Josh are standing 15 feet apart, Josh and Katrina are
standing 12 feet apart, and Katrina and Yana are standing 9 feet apart.
Tree joins the game and stands between Yana and Josh.
What is the shortest possible distance between Trae and Katrina?