1. Calculate the circumference of the circle first: r =10cmc = 2π r = 2x3.14x30 =188.4 (cm).

We have walked halfway in half an hour, so divide by 2= 188.4/2=94.2 (cm).

A wall clock with a minute length of 10 cm. After 30 minutes, the tip of the clock passed (94.2) cm.

2. Length is the circumference of the calculated excircle: calculated by the formula of circumference: 2x3. 14=6.28 (m). If it is changed to a square side length, it is 6.28/4= 1.57 (meters) (with four sides). The area is 1.57x65438+.

A wire just surrounds a circle with a diameter of 2 meters, and this wire is (6.28) meters long; If a square is formed, its side length is (1.57) meters and its area is (2.4649) square meters.

Application problem 1. The length of the other right angle is: 12×2/3=8 (cm).

The circular area is: 3.14× 8/2× 8/2 = 3.14×16 = 50.24 (square centimeter) (of course, it can also be 16π).

If you don't understand, please ask questions and hope to adopt them!