Rectangle inside semicircle

I have no clue what to do here......(Headbang)

A rectangle is inscribed in a semicircle of radius 5 cm. (One side of the rectangle is on the diameter of the semicircle and two of the vertices of the rectangle are on the semicircle)

1) Draw a model of this situation

2) Suppose the side of the rectangle which is on the diameter is 2 cm long. What will be the area of the rectangle?

3) Create a rule which can be used to find the length of the side of rectangle which is on the diameter of the semicircle when the area of the rectangle is known

4) Graph the function from #3 and use it to find possbiel lengths which will give an area of 24

5) Why would #4 be hard with algebra alone?