1. XY and YZ are diameters of two tangent circles and XY = 10 cm. Find YZ if the area of hte shaded region equals the area of hte unshaded region.

The answer is: 24.14, but how and why?

2. Find the diameters of the two smaller circles if the shaded area is 4/9 of the area of the larger circle which has a diameter of 12 cm.

Notes:These drawings are not EXACT as the real one because I used paint, however they really close.

The answer is 4 cm and 8 cm, but how and why...?

These questions are really hard. Nobody in my class were able to answer them.