免费圆面积计算器
根据半径或直径计算圆的面积和周长。
面积
78.5398
周长31.4159
直径10.0000
公式
How to Calculate the Area of a Circle
Formula
A = π × r²
Where:
The area is the space enclosed within the circle.
计算示例
Find the area of a circle with radius 5.
- 01A = π × 5²
- 02= π × 25
- 03= 3.14159 × 25
- 04≈ 78.5398
常见问题
How do you find the area of a circle?
Multiply π (pi, approximately 3.14159) by the square of the radius: A = πr².
How do you find the area if you know the diameter?
The radius is half the diameter. So A = π × (d/2)² = πd²/4.
学习