Area of Circle = (0.785) (Diameter) (Diameter)
– OR –
Area of Circle = (3.14) (Radius) (Radius)
Let’s take a look at this in action.
Here are two worked examples using each circle area formula for a circle with a diameter of 6 inches.
Example 1: Using the Diameter Formula
Formula:
Area = 0.785 × Diameter × Diameter
Calculation:
Area = 0.785 × 6 × 6
Area = 0.785 × 36
Area = 28.26 square inches
Example 2: Using the Radius Formula
Formula:
Area = 0.785 × Diameter × Diameter
Calculation:
Area = 3.14 × 3 × 3
Area = 3.14 × 9
Area = 28.26 square inches
Final Answer = 28.26 square inches
Both formulas give the same area.
This is one in a series that covers the basic formulas commonly found on Formula/Conversion Tables provided for reference during Water Treatment, Distribution, & Water Laboratory Exams.