What is the radius of a circle? Learn about the radius of a circle, including the formula for a radius, how to find and measure a radius, and examples of radii.

Learn to define the radius of a circle. Learn what the radius formula is and how to find the radius of a circle given area, diameter, or...

Example Problem 1 - How to Inscribe a Square in a Circle In the image below, the square is inscribed in the circle and the circle has a radius of 2 inches. Find the area and perimeter of …

The equation of a circle is the algebraic equality that describes it given its radius and its center. In this lesson, we saw two forms of the equation: the standard form and the center-radius form.

What is the diameter of a circle? Learn the formula, and see examples of how to find the diameter of a circle using the radius, circumference, or area.

Learn how to draw a circle with a given radius or diameter and see examples that walk through sample problems step-by-step for you to improve your geometry knowledge and skills.

Given the circumference, C, of a circle, the area can be found by dividing the circumference by 2, and multiplying that result by the radius. That is, A = (C / 2)r.

Learn how to inscribe an equilateral triangle in a circle, and see examples that walk through sample problems step-by-step for you to improve your math knowledge and skills.

Learn to define a quarter circle. Discover the area and perimeter of a quarter circle. Learn how to calculate the area and circumference of a...

Learn the definition of a chord of a circle in geometry. Explore how to find the length of a chord, the chord length formula, and the chord of a circle formula.