Radius: The radius of the great circle with R is small.

Diameter: the diameter of the big circle and the small circle D-

Circumference:

Region: s

Basis: R =? DD = 2R

c = 4A S = 2。

C length =(A+B)×2 S length = AB.

Category S = AH S3 = AH÷2

Step =(A+B)H÷2

Whole circumference:

C = π d = 2π rd = c ÷ pi

r = c÷pi÷2 = c÷2π= c÷6.28

Semicircular perimeter:

Half =πD2 \u+ D

=(PI÷2)D + D× 1

= 1.57d + D

= 2.57d BR p & gtC half =2πR÷2 +2

= Sunday +2

= 5. 14r

D = C half ÷2.57

R = half/5.14

Half the circumference:

c？ =πD÷2

? =2πR÷2 = NR

D =？ ×2π

R = C？ circumference ratio

Cycle length

CN = nπd = 2nπr

............

We should consider the relationship between distance, time, speed and surrounding areas, and the conditions and requirements of tourism.

Distance = speed × time

Rotational speed = distance ÷ time

Time = distance/speed

Journey = one week.

C = speed × time

Rotational speed = C÷ time

Time = C÷ speed

The whole area? A circle

s = NR ^ 2 = pi(d÷2)2

Semicircular area:

Half = NR 2 ÷ 2 = (π 2) R 2 = 1.57R2。

Annular area:

Ring -s = s = π R2 π R2 = π (R 2-R 2)

Semi-annular area:

In S semiring = S ring ÷ 2 = π (r 2-r 2) ÷ 2 =1.57 (r 2-r 2).

Perimeter and area of playground:

1, middle rectangle:

Transportation = C round +2

Small OP = S+S cycle length

2. Intermediate party:

Yun C = C wheel +2 D

S OP = S circle +S front