Find the area. :-)?

Take the diagram you were given, and draw in the inner and outer radii such that the inner radius meets the 70 ft line in a right angle and the outer radius hits one end of the 70 ft line. Mark the right angle, and then you'll see that the outer radius is the hypotenuse of a right triangle formed by the inner radius and half of the 70 ft line. Thus, you have r_inner^2 + 35^2 = r_outer^2 ==> r_outer^2 - r_inner^2 = 35^2 = 1225. Now, the area of an annular region such as this would be equal to the area of the inner circle subtracted from the area of the outer circle, or pi*r_outer^2 - pi*r_inner^2 = pi*(r_outer^2 - r_inner^2) = 1225*pi = 3,848 ft^2. It turns out that the inner and outer radii don't need to be measured. Any annular region with a chord of length 2L that is tangent to the inner circle will have an area equal to that of a circle with radius L.

I don't think you've given enough infomation. how big is the diameter of the hole in the middle? the 70 feet could be anywhere from the diameter of the carousel. maybe i don't get it!

Area = Pi x R squared

3.14 (Pi) x 1225 (35x35) = 3846.50 sq feet

R (radius) = 35, which is half the diameter ( D = 70ft )