Illustration of an 8-point star, or convex polygon, inscribed in a circle. This can also be described…

Illustration of a circle with a tangent drawn - a straight line perpendicular to a radius at its extremity.

Illustration of an equilateral triangle circumscribed about a circle. This can also be described as…

Illustration of triangle inscribed in circle. Or, circle circumscribed about triangle.

Illustration of an equilateral triangle inscribed in a circle. This can also be described as a circle…

An illustration showing a triangle with sides b, c, and d inscribed in a circle with radius r.

An illustration showing a triangle with angles A, C, and D inscribed in a circle which is tangent to…

Illustration showing a circle with an inscribed triangle and radii.

Illustration showing that a circle may be considered as made up of triangles whose bases form the circumference.

Illustration of a circle with two intersecting chords within the circumference. The angle formed is…

Illustration of a circle which illustrates that the tangents to a circle drawn from an external point…

Illustration of a circle with unequal chords, which are unequally distant from the center.

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane. The…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane. All…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane. At each…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane with…

Illustration of a unit circle (circle with a radius of 1) superimposed on the coordinate plane. All…

Illustration showing a circle with various chords and tangents drawn.

Illustration showing a circle with various chords and tangents drawn.

Illustration showing an equilateral triangle inscribed in a circle.

Illustration showing a circle with an inscribed and circumscribed quadrilateral.

Illustration showing a circle with an inscribed quadrilateral and triangles formed by extended chords.

Circular rosette-like pattern made with 12 overlapping congruent circles tangent to a center circle…

Circular rosette-like pattern made with 24 overlapping congruent circles tangent to a center circle…

A large circle containing 3 smaller congruent circles. The small circles are externally tangent to each…

A large circle containing 3 smaller congruent circles. The small circles are externally tangent to each…

A large circle containing 4 smaller congruent circles. The small circles are externally tangent to each…

A large circle containing 4 smaller congruent circles. The small circles are externally tangent to each…

Circular rosette-like pattern made with 48 overlapping congruent circles tangent to a center circle…

A sequence of five circles tangent to each other at a point. The radius decreases by one half in each…

A large circle containing 7 smaller congruent circles. The small circles are externally tangent to each…

A large circle containing 7 smaller congruent circles. The small circles are externally tangent to each…

7 congruent circles. 6 of the circles are equally placed about the center circle. The circles are externally…

Illustration showing angles formed by two secants, two tangents, or a tangent and a secant, drawn to…

Illustration used to prove "If two circumferences meet at a point which is not on their line of centers,…