Area of a Circle Calculator
Use this calculator to find the area of a circle when you know its radius.
Area tells you how much space the circle covers (in square units).
In the diagram, the radius is labeled r.
Step-by-step method
- Identify what is given.
- Write the formula.
- Substitute the value and calculate the area.
Formula:
Example 1: r = 5
Step 1 - Identify what is given.
In this problem: The given radius is r = 5.
Step 2 - Write the formula.
In this problem: Use the circle area formula: A = πr².
Step 3 - Substitute the value and calculate the area.
In this problem: Substitute r = 5: A = π × 5² = 78.53981634.
Final answer: A = 78.53981634
Example 2: r = 3.5
Step 1 - Identify what is given.
In this problem: The given radius is r = 3.5.
Step 2 - Write the formula.
In this problem: Use the circle area formula: A = πr².
Step 3 - Substitute the value and calculate the area.
In this problem: Substitute r = 3.5: A = π × 3.5² = 38.48451001.
Final answer: A = 38.48451001
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