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# The Meaning of Diameter in Geometry

The diameter of a circle is the straight line passing through the center of the circle and connecting two opposite points on the circumference. In geometry, this straight line is called a chord. A diameter can also be extended to pass through any two points on the circle's circumference, even if those points are not on opposite sides of the center.

The word "diameter" comes from Greek and literally means "measure across." The diameter of a circle is always twice the length of its radius. The radius is the straight line from the center of a circle to any point on its circumference.

You can easily find the diameter or radius of a circle if you know the length of its circumference. The circumference is the distance around a circle and is equal to pi times the diameter (C = πd) or pi times two times the radius (C = 2πr). Pi is a mathematical constant equal to 3.1415926535897932384626433832795028841971693993751058209756...

If you don't want to use pi, you can just round it off to 3.14.

To find either the diameter or radius when given the other, simply divide by two or multiply by two, respectively. This works because as we said earlier, the diameter is always twice the radius. So, if r = 4 inches, then d = 8 inches because 2(4) = 8. Similarly, if d = 10 feet, then r = 5 feet because 10/2 = 5.

## FAQ

### What is a simple definition of diameter?

The diameter of a circle is the length of a line segment that passes through the center of the circle and connects two points on the circumference of the circle.

### How do you find the diameter in geometry?

There are a few different ways to find the diameter of a circle in geometry. The most common way is to use the formula d=2r, where d is the diameter and r is the radius. Another way to find the diameter is to use the circumference of the circle divided by pi, or C/pi. Lastly, you can use the area of the circle divided by pi, or A/pi. All of these methods will give you the same answer.

### What is diameter and example?

The diameter of a circle is the length of a line segment that passes through the center of the circle and connects two points on the circumference of the circle. An example of a diameter would be a line segment that passes through the center of a circle and has its endpoints on the circumference of the circle.