📚 Topic Summary
This worksheet focuses on the relationship between a circle's circumference, radius, and diameter. The circumference is the distance around the circle. The diameter is the distance across the circle through the center, and the radius is the distance from the center to any point on the circle. The key formula we'll use is: $C = 2 \pi r$, where $C$ is the circumference, $r$ is the radius, and $\pi$ (pi) is approximately 3.14159.
To find the radius when you know the circumference, you can rearrange the formula to: $r = \frac{C}{2 \pi}$. Once you have the radius, the diameter is simply twice the radius: $d = 2r$. Let's practice these calculations!
🧠 Part A: Vocabulary
Match the term with its definition:
- 📏 Circumference
- ➗ Radius
- ⚫ Diameter
- 🥧 Pi ($\pi$)
- 🔄 Circle
Definitions:
- a) The distance from the center of the circle to any point on the circle.
- b) The ratio of a circle's circumference to its diameter, approximately 3.14159.
- c) The distance around the circle.
- d) A round plane figure whose boundary (the circumference) consists of points equidistant from the center.
- e) The distance across the circle through the center.
✏️ Part B: Fill in the Blanks
Complete the following sentences:
- The ____________________ is the distance around a circle.
- The ____________________ is the distance across a circle through its center.
- The ____________________ is half the diameter.
- The formula to calculate the circumference is $C = 2 \pi$ __________.
- To find the radius, divide the ____________________ by $2 \pi$.
🤔 Part C: Critical Thinking
Imagine you have a circular pizza with a circumference of 50 inches. You want to cut it into slices. Would knowing the radius or diameter help you slice the pizza evenly? How?