# 1. How to find the area of a circle with the radius

What is its area?

Formula for the area of a circle: A = π.R2.

• Area of a circle: A
• π ≈ 3,14159

## 2. How to find the area of a circle with the diameter

Know: Diameter

What is its area?

Formula for the area of a circle: $A = \frac{1}{4}.\pi .{D^2}$

• Area of a circle: A
• π ≈ 3,14159
• Diameter: D

Note: D = AB = 2R => D/2 = R => A = π.(D/2)2. = 0,25.π.D2