Radius
The radius of a circle is the distance from the center of the circle to any point on the circle. It is represented by the letter "r". The radius is a fundamental aspect of a circle and is used in various calculations involving circles.
Calculating the Radius
To calculate the radius of a circle, you can use the formula:
r = C / (2π)
Where r is the radius and C is the circumference of the circle, and π is a constant approximately equal to 3.14159.
Relationship with Diameter
The radius of a circle is half the length of the diameter. So, the diameter (d) of a circle is related to the radius by the formula:
d = 2r
Study Guide
- Understand the concept of the radius as the distance from the center of a circle to any point on the circle.
- Learn the formula for calculating the radius: r = C / (2π)
- Understand the relationship between the radius and the diameter: d = 2r
- Practice calculating the radius and diameter of circles with different circumferences.
- Apply the concept of the radius in solving problems related to circles, such as finding the area or circumference of a circle.
Understanding the radius is crucial in grasping the concepts of circles and is essential for further studies in geometry and trigonometry.
.◂Math Worksheets and Study Guides Eighth Grade. Perimeter and area
Study Guide
Perimeter and area 
Worksheet/Answer key
Perimeter and area Worksheet/Answer key
Perimeter and area Worksheet/Answer key
Perimeter and area Worksheet/Answer key
Perimeter and area
Worksheet/Answer keyWorksheet/Answer keyWorksheet/Answer keyWorksheet/Answer keyThe resources above cover the following skills:
Geometry (NCTM)
Analyze characteristics and properties of two- and three-dimensional geometric shapes and develop mathematical arguments about geometric relationships.
Precisely describe, classify, and understand relationships among types of two- and three-dimensional objects using their defining properties.
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.