What is diameter?

The diameter of a circle or sphere is defined as any straight line segment that passes through the center of the circle or sphere and whose endpoints lie on the circle or sphere. It is a fundamental concept in geometry.

Here's a breakdown of key aspects:

• Definition: The diameter is a line segment that connects two points on the circle (or sphere) and passes through the center of the circle (or sphere).
• Relationship to Radius: The diameter is always twice the length of the radius. Mathematically, d = 2r, where d is the diameter and r is the radius.
• Longest Chord: The diameter is the longest chord of the circle. A chord is a line segment that connects any two points on a circle.
• Applications: The diameter is used in various calculations related to circles and spheres, such as finding the circumference (C = πd) and the area of a circle (A = π(d/2)²). It's also used in determining the surface area and volume of spheres.
• Symbol: The symbol for diameter is often "⌀" (Unicode character U+2300), which looks like a circle with a diagonal line through it. Alternatively, "d" or "D" are commonly used.