Needed: Math Help

I am stuck, completely stuck on two math problems involving the area of circle. I am working these problems because I have discovered that math goes much more smoothly with Curly Girl if I have already figured out the puzzles ahead of time. You see, Curly Girl gets rather frustrated and hates asking for help when she makes a mistake in math. Likewise, trying to solve a problem myself and explain it to her at the same time doesn't always go very well for me either. My daughter and I being confused and frustrated together is not a good combination. So, to head off some issues, I have taken to working the problems ahead of time myself.

Today, however, I am utterly confused. I have tried everything I can think of, including using the answers and working backward. I still can't figure out how to solve them, though. So I am hoping that one of you can help me.
Both problems are from page 58 of the Singapore Math Grade 6 Challenging Word Problems Book, U.S. Edition. By the way, the answer to #14 is 700 square cm, and the answer to #15 is 119.652 square cm. If you need a refresher, Area of a circle = pi times the radius squared; Circumference of a circle = pi times the diameter.

If you figure either or both of them out, please leave a comment to let me know how you did it. If you are unable to leave a comment on here, feel free to send me a Facebook message.

Thank you! Thank you! Thank you!