Answer:
Radius:
radius is always half the length of its diameter. For example, if the diameter is 4 cm, the radius equals 4 cm ÷ 2 = 2 cm.
Diameter:
2 times the radius is the circle's diameter.
Circumference:
The formula is simply this: C = πd. In this equation, "C" represents the circumference of the circle, and "d" represents its diameter. That is to say, you can find the circumference of a circle just by multiplying the diameter by pi.the formula for circumference of a circle is 2 x pi x r(radius).
