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

Let me know if you want help with a specific problem!