7) What is the diameter and area of a circle with a circumference of 6.28?

Circumference “c” = 2пr, Area of a circle “a” = пr², where п = 3.14and r = radius (half of a diameter “D”)

c = 2пr, so to find “r”, you have to make “r” subject of formula by moving “2п” to the other side. when you go to the other side, addition becomes subtraction, multiplication becomes division, and vice versa.

Since “2п” is a multiplication to “r”, it will become a division at the other side

c/ 2п = r

6.28/ (2 x 3.14) = r

6.28/6.28 = r

1 = r; so if the radius  “r” = 1, then the diameter “D” = 2 (since radius is half of diameter 1 x 2 = 2)

a = пr²

a = 3.14 x 1²

so the area of the circle = 3.14