Question

Help I dont understand how to do this

Answer 1

the formula for circumstance of a circle is:

C= 2×pi×r or C= pi×d (the diameter actually consists of 2 radiuses)

1.

C= pi×7

≈21.99

2.

C= 2×pi×9

=18×pi

≈56.55

3.

C= 2×pi×5

=10×pi

≈31.42