1. The radius of the great circle is three times that of the small circle, and the area of the great circle is 84.78 square centimeters. How many square centimeters is the area of this small circle? (formula)

84。 78/9 = 9.42 square centimeters

2. The radius of the big circle is twice that of the small circle, the area of the big circle is more than that of the small circle 12 cm2, and the area of the small circle is () cm2. (Fill in the blanks)

The radius of a big circle is twice that of a small circle, the area of a big circle is three times that of a small circle, and the area of a small circle is (12/3 = 4) square centimeters.

3.c semicircle =15.42m (area)

3. 14*R+2R= 15.42

R= 15.42/5. 14=3

Area = 3.14 * 3 * 3/2 =14.13.