People's Education Press, the sixth grade of primary school mathematics, Volume II, exercises P53 pages of answers before and after class synchronously.
Their circumference: (10+5.7)*2=3 1.4 cm.
Rectangular area: 10*5.7=57 cm2.
Circle: the radius is 3 1.4/3. 14/2 = 5cm, 3.14 * 5 * 5 = 78.5cm.
Square: The side length is 3 1.4/4 = 7.85cm, 7.85 * 7.85 = 61.6225cm..