Bell Ringer Write an example of each of the following: Radius ____ Secant ____ Tangent ____ Chord ____ Diameter ____ Minor arc ____ Major arc ____ Central angle ____ Inscribed angle ____ Center ____

Quick Review of Definitions Arc Length Wednesday, May 4, 2016 Quick Review of Definitions

Chord a segment whose endpoints lie on a circle A B AB

Arc an unbroken part of a circle

Minor Arc an arc that is less than half of a circle to name, use 2 points

Major Arc an arc that is more than half of a circle to name, use 3 points

Central Angle an angle whose vertex is at the center of a circle

Inscribed Angle an angle whose vertex is on a circle and whose sides are chords of the circle

Tangent a line, ray, or segment that is in the same plane as the circle, but intersects the circle in only one point

Secant a line, ray, or segment that contains a chord

Arc Length Arc Length is a portion of the circumference because everything is proportional when it comes to circles! You need to know the central angle that intercepts your arc to set up your proportion.

Examples Find the arc length: 1. Radius 5cm, central angle 50o Find the circumference: 3. Central angle 55o, arc length 5.5cm 4. Central angle 60o, arc length 3.82m Find the central angle: 5. Arc length 45ft, radius 12ft 6. Arc length 30in, radius 14in

Assignments Classwork: Geometry book p. 686-688 #13-47 odd Homework: Circumference and Arc Length

Exit Ticket 1. How does the proportion for arc length compare with the proportion for arc measure? 2. What is the difference between arc length and arc measure?