Circles: Angles, Arcs and Chords

Front

What is a circle?

Back

A circle is a shape consisting of all points in a plane that are at a given distance from a fixed point, called the center.

Front

What is the radius of a circle?

Back

The radius is the distance from the center of the circle to any point on its circumference.

Front

What is the diameter of a circle?

Back

The diameter is twice the length of the radius and is the longest distance across the circle, passing through the center.

Front

What is a chord in a circle?

Back

A chord is a line segment whose endpoints lie on the circumference of the circle.

Front

What is an arc in a circle?

Back

An arc is a portion of the circumference of a circle.

Front

What is the measure of a central angle?

Back

A central angle is the angle whose vertex is at the center of the circle and whose sides are radii.

Front

What is the relationship between the central angle and the arc it subtends?

Back

The measure of the arc is equal to the measure of the central angle that subtends it.

Front

What is an inscribed angle?

Back

An inscribed angle is formed by two chords in a circle which have a common endpoint.

Front

What is the relationship between an inscribed angle and the arc it intercepts?

Back

The measure of an inscribed angle is half the measure of the intercepted arc.

Front

What is the angle formed by two tangents drawn from a point outside the circle?

Back

The angle formed is equal to half the difference of the measures of the intercepted arcs.