Can't answer the first q. It is too vague.
What is the formula for getting the AREA of a circle?
It is πr²
Example:
Radius / R = 3
π(r)²
3.14(3)²
3.14(9)
28.26 so the area is 28.26
What is the fomula for getting the circle radius?
It is √A/π
Example:
Area / A = 28.26
√A/π
√28.26/3.14
√9
3 so the radius is 3
What is the formula for getting the circle diameter?
It is 2r
Example:
Radius / R = 3
2(3)
6 is the diameter of the circle
What is the formula for getting the circumference of a circle?
That is 2πR for short terms, it is 6.28(R) since 2(3.14) = 6.28
Example:
R = 3
2πR
2(3.14)(3)
6.28(3)
18.84 is the circumference of the circle.
