1. Activate Prior Knowledge CFU
Learning Objective
We will determine1 how to use the Central Angles and Inscribed Angles to find the arc length.
What are we going to do?
What is determine means?_____.
CFU
Activate Prior Knowledge
A chord is a segment whose endpoints lie on a circle (CA).
A central angle is an angle with measure less than or equal to 180° whose vertex lies at the center of a circle ( AOB).
An inscribed angle is an angle whose vertex lies on a circle and whose sides contain chords of the circle ( ACB)
Circles
On your whiteboard, Name the following in the figure, Z is the center of the circle.
Activate Prior Knowledge CFU
Students, you already know how to identify Chord, Central, and inscribed angles. Today, we will learn how to find the measurement of those angles.
Make Connection
1 Figure out
Vocabulary

2. CFU Twice of Size Half of Size
Concept Development
Twice of
Size
Half of
Size
Think-Pair-Share: A explain to B, what is the difference between Inscribed Angle and Central Angle?
CFU

3. 1. Identify the following on your whiteboard:
Skill Development/Guided Practice
An arc is part of a circle. A semicircle is an arc that is half the circle. The measure of an arc is equal to the measure of the central angle that intercepts it.
1. Identify the following on your whiteboard:
2. Find the unknown value on your whiteboard:
How did I/you find arc MJ?
How did I/you find angle LJK?
How did I/you find angle LNK?
CFU 1 2 3

4. 1. Identify the following on your whiteboard:
Skill Development/Guided Practice
An arc is part of a circle. A semicircle is an arc that is half the circle. The measure of an arc is equal to the measure of the central angle that intercepts it.
1. Identify the following on your whiteboard:
2. Find the unknown value on your whiteboard:
How did I/you find arc IJ?
How did I/you find angle IJK?
How did I/you find angle JKL?
CFU 1 2 3

5. If the measure of an arc is equal to the measure of its central angle,
Relevance Reason #1: Help you read the graph
The circle graph shows how a typical household spends money on energy. If a typical household spends 9% of its money on energy for its washer
and dryer, what is
If the measure of an arc is equal to the measure of its central angle, 
Relevance Reason #2: Knowing how to find Central Angles and Inscribed Angles will help you do well on tests: (PSAT, SAT, ACT, GRE, GMAT, LSAT, etc..).
Sample Item
In the figure, O is the center of the circle.

6. What did you learn today about how to use the Central Angles and Inscribed Angles to find the arc length.
Word Bank
Circle
Intercepted
Inscribed Angle
Arc
Diameter
SUMMARY CLOSURE
Today, I learned how: