Circle Geometry Concepts

This video tutorial covers the area and circumference of circles and sectors. It introduces basic circle terminology such as radius, diameter, and chord, and explains formulas for calculating area and circumference. The lesson includes four examples, ranging from basic circle calculations to more complex shapes and sectors, providing a comprehensive understanding of circle geometry.

Which of the following is a segment that starts and ends on the circle?

• Diameter

• Radius

• Tangent

• Chord

What is the formula for the area of a circle?

• πd

• πr²

• 2πd

• 2πr

If the diameter of a circle is 10, what is its circumference?

• 5π

• 20π

• 10π

• 15π

In the example problem, what was the first step to find the area of a circle given its circumference?

• Multiply by π

• Divide by 2

• Divide by π

• Square the radius

How many small half circles make up one and a half circles?

• Four

• Three

• One

• Two

What is a sector of a circle?

• A full circle

• A line segment

• A slice of a circle

• A tangent

How do you calculate the area of a sector?

• πd

• (θ/360)πr²

• 2πr

• πr²

What fraction of a circle is a quarter circle?

• 1/5

• 1/4

• 1/3

• 1/2

In the final example, what shape was used to calculate the area by subtraction?

• Pentagon

• Square

• Triangle

• Rectangle

What is the radius of a circle if its diameter is 10?

• 15

• 20

• 10

• 5