To find the diameter of a circle, you can use one of the following methods depending on the information you have:
1. Using the Radius
- The diameter is twice the radius.
- Formula:
Diameter=2×Radius\text{Diameter}=2\times \text{Radius}Diameter=2×Radius
2. Using the Circumference
- If you know the circumference (the distance around the circle), use the formula:
Diameter=Circumferenceπ\text{Diameter}=\frac{\text{Circumference}}{\pi}Diameter=πCircumference
- Here, π≈3.1416\pi \approx 3.1416π≈3.1416.
3. Using the Area
- If you know the area of the circle, use the formula:
Diameter=2×Areaπ\text{Diameter}=2\times \sqrt{\frac{\text{Area}}{\pi}}Diameter=2×πArea
Example:
If the radius of a circle is 5 cm, then the diameter is:
2×5=10 cm2\times 5=10\text{ cm}2×5=10 cm
If the circumference is 31.4 cm, then the diameter is:
31.43.1416≈10 cm\frac{31.4}{3.1416}\approx 10\text{ cm}3.141631.4≈10 cm
If the area is 78.5 cm², then the diameter is:
2×78.53.1416=2×5=10 cm2\times \sqrt{\frac{78.5}{3.1416}}=2\times 5=10\text{ cm}2×3.141678.5=2×5=10 cm
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