Circle Geometry: Verify that Diameter = 2 × Radius

The diameter of a circle is defined as the distance across the circle through its center. It is directly related to the radius, which is the distance from the center to a point on the circumference of the circle.

By the standard definition in geometry, the diameter ($d$) of a circle is expressed in terms of its radius ($r$) as:

$d = 2r$

This equation clearly states that the diameter is twice the length of the radius. Hence, the statement, “The diameter of a circle is twice as long as its radius,” aligns with this fundamental geometric property.

Therefore, the statement is True.