Arcs and Angles in Circles

Front

What is the definition of an arc in a circle?

Back

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

Front

What is the relationship between the angle formed by two tangents from a point outside a circle and the intercepted arc?

Back

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

Front

What is the measure of a central angle in a circle?

Back

A central angle is equal to the measure of the arc it intercepts.

Front

What is the formula for finding the measure of an inscribed angle?

Back

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

Front

If two chords intersect inside a circle, how do you find the measure of the angles formed?

Back

The measure of each angle is equal to half the sum of the measures of the arcs intercepted by the angle and its vertical angle.

Front

What is a tangent line to a circle?

Back

A tangent line is a line that touches the circle at exactly one point.

Front

How can you prove that a line is tangent to a circle?

Back

A line is tangent to a circle if it is perpendicular to the radius drawn to the point of tangency.

Front

What is the relationship between the angles formed by two secants that intersect outside a circle?

Back

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

Front

What is the measure of an angle formed by a tangent and a chord?

Back

The measure of the angle is equal to half the measure of the intercepted arc.

Front

If the measure of arc AB is 80°, what is the measure of the inscribed angle that intercepts arc AB?

Back

The measure of the inscribed angle is 40°.