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# What is the area of a circle with diameter 18.9 centimeters?

Here is the answer to questions like: how to find the area of a circle with diameter 18.9 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.

### Inputs:

 Radius: or Diameter: or Circumference: Unit: centimeter foot inch kilometer meter mile yard

### Result:

The area of a circle with diameter 18.9 is 280.5520779472

### Area of a cicle in terms of radius:

Area = π . r2 = 3.14 × 9.452 = 280.55 square centimeters.

### In terms of diameter:

Area = π . (d/2)2 = 3.14 × (18.9/2)2 = 3.14 × (9.45)2 = 280.55 square centimeters.

### In terms of circumference:

Area = C2/(4π) = 59.382/ = 3525.52/(4 × 3.14) = 3525.52/(12.56) = 280.55 square centimeters.

Note: for simplicity, some results may be rounded to nearest hundredth and π was rounded to 3.14. See formula details below in this page.

### A circle of radius = 9.45 or diameter = 18.9 or circunference = 59.376101152847 centimeters has an area of 280.5520779472 square centimeters which is equal to:

• 2.805520779472E-8 square kilometers (km²)
• 0.02805520779472 square meters (m²)
• 6.9325928242549E-6 acres (ac)
• 2.805520779472E-6 hectares (ha)
• 1.0832176287898E-8 square miles (mi²)
• 0.033553749269394 square yards (yd²)
• 0.30198374342455 square feet (ft²)
• 43.485659053134 square inches (in²)
• ## Formula for area of a circle

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

### 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.

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 (cm²), if in inches, will get the answer in square inches (in²) and so on ...

Circumference is often misspeled as circunference.

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

### Disclaimer

While every effort is made to ensure the accuracy of the information provided on this website, we offer no warranties in relation to these informations.