To help you remember the formulas for radius, diameter, and circumference, here’s an easy way to do it using a fun phrase:

1. Radius (r): Think of "Ray to Center."

   • This means the radius is the distance from the center of the circle to the edge.
   • Formula: ( r = \frac{d}{2} ), where ( d ) stands for diameter.

2. Diameter (d): Just remember "Double the Ray."

   • The diameter is twice the radius.
   • Formula: ( d = 2r ).

3. Circumference (C): Picture a big circle and remember "C = π * d" or "C = 2 * π * r."

   • This shows how to find the distance around the circle.
   • Formula: ( C = πd ) or ( C = 2πr ).

You can even draw a circle and label these parts—it will make it easier to remember!