I don't know if the area is 9 or 15 and if my process is correct thank you so much!?

[4 points] A rectangle is placed with one side lying along the r-axis and the side opposite to this side running between two points on the semicircle y = v9 -r2. How must this rectangle be placed in order for its area to be as large as possible. What is the maximum possible area? Explain your reasoning clearly. -2