How to Find the Area and Circumference of Circles? (+FREE Worksheet!)

Related Topics

• How to Find Arc Length and Sector Area
• How to Find Equation of a Circle
• How to Find the Center and the Radius of Circles

Step by step guide to solve Circles

• In a circle, variable \(r\) is usually used for the radius and \(d\) for diameter and \(π\) is about \(3.14\).
• Area of a circle \(\color{blue}{=πr^2}\)
• Circumference of a circle \(\color{blue}{=2πr}\)
  

Circles – Example 1:

Find the area of the circle.

Solution:

Use area formula: Area \(=πr^2\),
\(r=6\) \(in\), then: Area \(=π(6)^2=36π\)

\(π=3.14\), then: Area \(=36×3.14=113.04\) \(in^2\)

Circles – Example 2:

Find the Circumference of the circle.

Solution:

Use Circumference formula: Circumference \(=2πr \)
\(r=9 \) \(cm\) , then: Circumference \(=2π(9)=18π \)
\(π=3.14\), then: Circumference \(=18×3.14=56.52\) \(cm\)

Circles – Example 3:

Find the area of the circle.

Solution:

Use area formula: Area \(=πr^2\),
\(r=4\) \(in\), then: Area \(=π(4)^2=16π\)

\(π=3.14\), then: Area \(=16×3.14=50.24\) \(in^2\)

Circles – Example 4:

Find the Circumference of the circle.

Solution:

Use Circumference formula: Circumference \(=2πr \)
\(r=6 \) \(cm\) , then: Circumference \(=2π(6)=12π \)
\(π=3.14\), then: Circumference \(=12×3.14=37.68\) \(cm\)

Exercises for Solving Circles

Find the area and circumference of each circle. \((\pi=3.14)\)

Download Circles Worksheet

1. \(\color{blue}{Area: \ 50.24 \ in^2 , \ Circumference: \ 25.12 \ in}\)
2. \(\color{blue}{Area: \ 1,017.36 \ cm^2, \ Circumference: \ 113.04 \ cm}\)
3. \(\color{blue}{Area: \ 78.5 \ m^2, \ Circumference: \ 31.4 \ m}\)
4. \(\color{blue}{Area: \ 379.94 \ cm^2 , \ Circumference: \ 69.08 \ cm}\)