# What is the area of a circle with diameter 28 centimeters?

Here is the answer to questions like: how to find the area of a circle with diameter 28 centimeters?

Use the this circle area calculator below to find the area of a circle given its diameter, or other parameters. To calculate the area, you just need to enter a positive numeric value in one of the 3 fields of the calculator. You can also see at the bottom of the calculator, the step-by-step solution.

### Area of a Circle Calculator

## Formula for area of a circle

Here a three ways to find the area of a circle (formulas):

### Circle area formula in terms of radius

### Circle area formula in terms of diameter

### Circle area formula in terms of circumference

See below some definitions related to the formulas:

### Circumference

Circumference is the linear distance around the circle edge.

### Radius

The radius of a circle is any of the line segments from its center to its perimeter. The radius is half the diameter or r = ^{d}/_{2}.

### Diameter

The diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. The diameter is twice the radius or d = 2r.

### The Greek letter π

π represents the number Pi which is defined as the ratio of the circumference of a circle to its diameter or π = ^{C} / _{d}. For simplicity, you can use Pi = 3.14 or Pi = 3.1415. Pi is an irrational number. The first 100 digits of Pi are: 3.1415926535 8979323846 2643383279 5028841971 6939937510 5820974944 5923078164 0628620899 8628034825 3421170679 ...

### Note:

If you input the radius in centimeters, you will get the answer in square centimeters (cmÂ²), if in inches, will get the answer in square inches (inÂ²) and so on ...

Circumference is often misspeled as circunference.

You can use our area unit converter to see the results in other units.

## Sample Circle Area Calculations

- Area of a Circle with circumference 4.5 yard
- Area of a Circle with diameter 8.4 centimeters
- Area of a Circle with diameter 5.8 feet
- Area of a Circle with circumference 2.7 mm
- Area of a Circle with circumference 18.6 yard
- Area of a Circle with radius 11.3 inches
- Area of a Circle with radius 2.4
- Area of a Circle with circumference 7.85 kilometers
- Area of a Circle with circumference 19.8 miles
- Area of a Circle with diameter 3.1 feet

- Area of a Circle with circumference 14.13 centimeters
- Area of a Circle with diameter 1.4 units
- Area of a Circle with diameter 2.9 feet
- Area of a Circle with radius 20 kilometers
- Area of a Circle with radius 14.5 miles
- Area of a Circle with circumference 16.8 yard
- Area of a Circle with circumference 14.8 miles
- Area of a Circle with diameter 8.6 units
- Area of a Circle with diameter 16.7 miles
- Area of a Circle with circumference 29.83 yard

- Area of a Circle with diameter 9.4 kilometers
- Area of a Circle with diameter 18.4 meters
- Area of a Circle with diameter 49 miles
- Area of a Circle with diameter 1.8 feet
- Area of a Circle with diameter 84 kilometers
- Area of a Circle with diameter 19.3
- Area of a Circle with radius 37 units
- Area of a Circle with circumference 7 pi inches
- Area of a Circle with radius 19 kilometers
- Area of a Circle with diameter 4.4 centimeters