Welcome to our Pi day adventure! Before we can eat our pies we have to help young Radius save his father, Sir Cumference. Let’s help Radius solve the riddle of the circle and save Sir

Cumference. So put your thinking caps on and let’s get started.

Sir Cumference and Radius are having lunch together. What is their relationship?

Radius is his son

As we continue our adventure, try to think about the relationship between the circumference of a circle and its radius

In mathematics, what does “radius” mean?

The radius of a circle is defined as a line from the center of a circle to a point on the circle

Can you find the radius in the circle?

Sir Cumference’s tail curls up to form a circle. What do you call the distance around a circle?

The distance around a circle is called the CIRCUMFERENCE.

Find the circumference of a circle whose diameter measures 25 yd

25 yd

C = dπ

C = 25 yd • π

C = 25 π yd

If the circumference of a circle is 24π find the length of the radius.

?

Radius = 12

…Measure the middle …

what part of the circle does this part of the riddle refer to?

… and circle around…

This refers to the circle’s ______________

DIAMETER

Circumference

Find the hidden circles…

There’s one more…

154 = 49 π _ _ 49 49

3.14 = π

Evaluate the formula: C= dπ

Prove it… Multiply each diameter by three. Is the circumference approximately three times the value of the diameter?

3.5 • 3 = 10.5 7 • 3 = 21

14 • 3 = 42 17.5 • 3 = 52.5