The area (A) of a circle is given by the formula:

A = π * r^{2}

Where π (pi) is a constant approximately equal to 3.14159, and r is the radius of the circle.

The circumference (C) of a circle is given by the formula:

C = 2 * π * r

Where π (pi) is a constant approximately equal to 3.14159, and r is the radius of the circle.

Here are some key points to remember when working with the area and circumference of circles:

- The radius of a circle is the distance from the center to any point on the circle.
- The diameter of a circle is the distance across the circle passing through the center.
- Remember to use the value of π as approximately 3.14159 in your calculations.
- To find the area of a circle, use the formula A = π * r
^{2}. - To find the circumference of a circle, use the formula C = 2 * π * r.

Calculate the area and circumference of circles with the following given radii:

- Given a circle with radius r = 5 units.
- Given a circle with radius r = 8.5 units.
- Given a circle with radius r = 12.3 units.

Study GuideArea and Circumference of Circles Activity LessonArea of Circles Activity LessonCircumference of Circles Worksheet/Answer key

Area and Circumference of Circles Worksheet/Answer key

Area and Circumference of Circles Worksheet/Answer key

Area and Circumference of Circles Worksheet/Answer key

Area and Circumference of Circles

Geometry (NCTM)

Use visualization, spatial reasoning, and geometric modeling to solve problems.

Use geometric models to represent and explain numerical and algebraic relationships.

Measurement (NCTM)

Apply appropriate techniques, tools, and formulas to determine measurements.

Select and apply techniques and tools to accurately find length, area, volume, and angle measures to appropriate levels of precision.

Develop and use formulas to determine the circumference of circles and the area of triangles, parallelograms, trapezoids, and circles and develop strategies to find the area of more-complex shapes.

Connections to the Grade 6 Focal Points (NCTM)

Measurement and Geometry: Problems that involve areas and volumes, calling on students to find areas or volumes from lengths or to find lengths from volumes or areas and lengths, are especially appropriate. These problems extend the students' work in grade 5 on area and volume and provide a context for applying new work with equations.