① Look at the length of Wukong's golden hoop as the radius, which is1.8m.
What is the length of one end of the golden hoop?
In fact, it is to find the circumference of a circle with a radius of 1.8m: formula c = 2π r.
(r is the radius and c is the circumference)
② What is the area swept by the golden hoop?
Find its area: formula S=πr?
(s is the area)
This question examines students' operations on the area and perimeter of a circle, and can be solved by mastering its formula!