Calculating the Area of a Circle

This page provides a comprehensive guide on how to calculate the area of a circle using various examples and scenarios. The fundamental formula for circular area calculation is introduced and applied to different problems.

Definition: The area of a circle is calculated using the formula A = πr², where A is the area, π (pi) is approximately 3.14, and r is the radius of the circle.

The page presents several examples of area calculations:

1. For a circle with a diameter of 10 cm:

   • First, the radius is determined by dividing the diameter by 2 (5 cm).
   • Then, the area is calculated: A = π × 5² = 78.5 cm².

2. For a circle with a radius of 2 m:

   • The area is directly calculated: A = π × 2² = 12.56 m².

3. For a semi-circle with a diameter of 4 cm:

   • The full circle area is calculated first: A = π × 2² = 12.56 cm².
   • Then, this result is divided by 2 to get the semi-circle area: 6.28 cm².

Highlight: When given the diameter, always divide it by 2 to find the radius before applying the area formula.

The page also includes a helpful tip for calculating areas of partial circles:

Example: To find the area of a semi-circle, calculate the full circle area and divide by 2. For a quarter circle, divide the full area by 4.

This information is particularly useful for students learning how to find the area of a circle with the diameter or radius, and how to adapt the formula for different circular segments.

Vocabulary:

• Radius: The distance from the center of a circle to its edge.
• Diameter: The length of a line through the center of a circle from one side to the other, equal to twice the radius.

The page serves as an excellent resource for understanding and practicing area of circle questions and answers, providing a solid foundation for more advanced geometric calculations.