For the larger wheels
Area = Pi (3.14) x r (radius) squared (multiplied by itself)
However for the smaller wheels you have the diameter, meaning that you will take the same steps, except you'll divide by 4.
Area = Pi (3.14)/4 x d (diameter) squared (multiplied by itself)
1.
R = 15
15 x 15 = 225
225 x 3.14 = 706.5
2.
D = 8
8 x 8 = 64
64 x 3.14/4 = 50.24
3.
R = 18
18 x 18 = 324
324 x 3.14 = 1017.36
4.
D = 10
10 x 10 = 100
100 x 3.14/4 = 78.5
5.
R = 20
20 x 20 = 400
400 x 3.14 = 1256
6.
D = 12
12 x 12 = 144
144 x 3.14/4 = 113.04
7.
R = 12
12 x 12 = 144
144 x 3.14 = 452.16
8.
D = 6
6 x 6 = 36
36 x 3.14/4 = 28.26
Please do keep trying problems like this if you are still having some trouble! I remember struggling a bit to learn calculating with radius vs. calculating with diameter.
I do hope you have a better understanding though. Always keep trying to learn! <3
