Ch 10 Circles

Front

What is a circle?

Back

A circle is a set of points in a plane that are equidistant from a fixed point called the center.

Front

What is the measure of a full circle in degrees?

Back

360°

Front

What is an arc in a circle?

Back

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

Front

How do you find the measure of an arc?

Back

The measure of an arc can be found using the central angle that subtends the arc.

Front

What is a tangent line to a circle?

Back

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

Front

What is the relationship between a tangent and a radius?

Back

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

Front

What is the formula for the circumference of a circle?

Back

C = 2πr, where r is the radius of the circle.

Front

What is the formula for the area of a circle?

Back

A = πr², where r is the radius of the circle.

Front

What is a central angle?

Back

A central angle is an 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.