An illustration showing a circle with radius r, diameter d, and chord c.

Illustration of a regular heptagon/septagon inscribed in a circle. This can also be described as a circle…

Illustration of a regular hexagon circumscribed about a circle. This can also be described as a circle…

Illustration of a regular hexagon inscribed in a circle. This can also be described as a circle circumscribed…

Illustration of a regular hexagon inscribed in a circle. This can also be described as a circle circumscribed…

Illustration of a regular nonagon circumscribed about a circle. This can also be described as a circle…

Illustration of a regular nonagon inscribed in a circle. This can also be described as a circle circumscribed…

Illustration of a regular octagon circumscribed about a circle. This can also be described as a circle…

Illustration of a regular octagon inscribed in a circle. This can also be described as a circle circumscribed…

Illustration of a regular pentagon circumscribed about a circle. This can also be described as a circle…

Illustration of a regular pentagon inscribed in a circle. This can also be described as a circle circumscribed…

Illustrations of a circle with secant AD and line BC tangent to it.

Illustration of circle with sector and segment used to find area.

Illustration of partial circle with sector and segment used to find area.

Illustration of a circle with a sector. "A sector of a circle is the space included between an arc and…

Illustration of a sector of a circle. A sector is the space between an arc and two radii drawn to the…

Illustration of circle with diameter and segment used to find area.

Illustrations of a circle with segment, semicircle, sector, quadrant, and central angles drawn.

Illustration of a square, with diagonals drawn, circumscribed about a circle. This can also be described…

Illustration of a square, with 1 diagonals drawn, circumscribed about a circle. This can also be described…

Illustration of a square circumscribed about a circle. This can also be described as a circle inscribed…

Illustration of a square inscribed in a circle. This can also be described as a circle circumscribed…

Illustration of a square inscribed in a circle. This can also be described as a circle circumscribed…

Illustration of a square, with diagonals drawn, inscribed in a circle. This can also be described as…

Illustration of a 6-point star (convex dodecagon) circumscribed about a circle. This can also be described…

Illustration of an 8-point star (convex polygon) circumscribed about a circle. This can also be described…

Illustration of a 5-point star inscribed in a circle. This can also be described as a circle circumscribed…

Illustration of a 6-point star created by two equilateral triangles (often described as the Star of…

Illustration of a 6-point star (convex dodecagon) inscribed in a circle. This can also be described…

Illustration of an 8-point star, created by two squares at 45° rotations, inscribed in a circle.…

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 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.