To find the area of a circle when you have the diameter, you first need to remember the formula for the area of a circle, which is:
Area = πr²
In this formula, r represents the radius of the circle. The radius is half of the diameter, so if you know the diameter (d), you can find the radius by using the formula:
r = d ÷ 2
Once you have the radius, you can substitute it back into the area formula. Here’s a step-by-step guide:
- Calculate the radius by dividing the diameter by 2.
- Square the radius (multiply the radius by itself).
- Multiply that result by π (approximately 3.14).
For example, if the diameter of the circle is 10 units:
- First, find the radius: r = 10 ÷ 2 = 5 units
- Then, square the radius: 5² = 25
- Finally, calculate the area: Area = π × 25 ≈ 78.5 square units
So, the area of the circle with a diameter of 10 units is approximately 78.5 square units.