Diameter is a straight line that passes through the center of a circle or a sphere and touches two opposite points on the circumference or surface. It is a measurement of the length of the line segment that extends from one point on the circumference or surface of the circle or sphere to its opposite point, passing through the center. The diameter is conventionally denoted by the symbol "d". It is a fundamental property of a circle or sphere and is used in various mathematical calculations and formulas involving circles and spheres.
