Slide 2: Remember: a circle is made up of 360 degrees. The distance around
a circle can be measured in degrees as can the angles formed within
The curved portion between any two points on a circle is an arc.
Slide 3: A semicircle is half of a circle.
Arc ACB and Arc ADB are semicircles.
A semicircle measures 1800.
A minor arc is a portion of the circle that is smaller than a semicircle.
Arc AB is a minor arc.
The degree measure is greater than 0o but less than 180o.
A major arc is a portion of the circle that is greater than a semicircle.
Arc CBA is a major arc.
The degree measure is greater than 180o but less than 360o.
Slide 4: An angle with a vertex at the center of the circle is a central angle.
<CPB is a central angle.
The measure of a central angle and its corresponding arc
If arc CB = 45o then <CPB = 450.
An angle with a vertex on the circle is an inscribed angle.
<DAB is an inscribed angle.
The measure of an inscribed angle is half the measure of the
arc formed by its endpoints.
If arc BD = 100o then <DAB = 500.