Central Angles

Front

What is a central angle?

Back

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

Front

How do you calculate the measure of an arc?

Back

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

Front

What is the relationship between a central angle and its intercepted arc?

Back

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

Front

If the measure of arc AB is 142°, what is the measure of the central angle subtending arc AB?

Back

The measure of the central angle is also 142°.

Front

What is the formula for finding the measure of an arc in a circle?

Back

The measure of an arc = (central angle in degrees) / 360 * (circumference of the circle).

Front

What is the total measure of all arcs in a circle?

Back

The total measure of all arcs in a circle is 360°.

Front

If two central angles are equal, what can be said about their intercepted arcs?

Back

The intercepted arcs are also equal.

Front

What is the measure of arc AD if the central angle is 38°?

Back

The measure of arc AD is 38°.

Front

How do you find the missing angle in a circle when given other angles?

Back

Use the fact that the sum of angles around a point is 360° or the sum of angles in a triangle is 180°.

Front

If the measure of arc WXZ is 231°, what is the measure of the central angle subtending arc WXZ?

Back

The measure of the central angle is also 231°.