Measure of a Surface Area
Number that expresses an area. This number is related to the unit of measure used.
Formula
The area of a circle is a number that expresses the measure of the surface area of the circle.- The formula to calculate this measure is: A = π[latex]{r^2}[/latex] = π[latex]\frac{d^2}{4}[/latex].
- The letter A represents the area of the circle.
- The letter r represents the radius of the circle.
- The letter d represents the diameter of the circle.
- The value of π is approximately 3.1416.
Examples
- To measure the rectangular surface area below, any of the four unconventional units of measure identified by the letters A to D can be used.
The area of the blue rectangle is equal to 4 A units, 8 B units, 24 C units or 48 D units. - Consider the circle below with a radius of 3 cm.
A = π[latex]{r^2}[/latex]
A ≈ 3.1416 × 3 × 3
A ≈ 28.2744 cm[latex]^{2}[/latex]