1. SEE SOMETHING, SAY SOMETHING
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SEE SOMETHING, SAY SOMETHING

2. Learning Objective
What are we going to do?
What is bisect means ___________.
CFU
We will Bisect1 angles and find the missing angle measurements.
Activate Prior Knowledge
An angle is a figure formed by two rays with the same endpoint. The common endpoint is the vertex of the angle. The rays are the sides of the angle. When an angle is named with three letters, the middle letter is the vertex.
ray
vertex
ray
Name the given angles 1. 2. 2
Students, you already know how to name an angle. Now, we will find the missing angle measurements.
Make Connection
1. With Letter of the Vertex: ______
2. With three letters,
vertex in the middle : ______
3. With the arc number : ______
1. With Letter of the Vertex: ______
2. With three letters,
vertex in the middle : ______
3. With the arc number : ______ 2
1 divide an angle into two equal parts.
Vocabulary

3. We use a protractor to measure an angle degree.
Concept Development
The distance around a circular arc is undefined until a measurement unit is chosen. Degrees (°) are a common measurement unit for circular arcs.
On your whiteboard, draw and label:
acute angle.
obtuse angle
right angle.
straight angle
What are the different ways to name an angle?
CFU
We use a protractor to measure an angle degree.
Classify ∠MXP, ∠LXN, and ∠NXP as acute, right, or obtuse.
How did you find the angle measurement using the protractor?

4. Find the value of x, given that m PQS = 110°.
Concept Development
An angle bisector is a ray that divides an angle into two angles that both have the same measure.
*The arcs in the figure show equal angle measures.
On your whiteboard, Find the value of x, given that mangle m PQS = 114°. Round the answer to one decimal place if necessary?
CFU
Find the value of x, given that m PQS = 110°.
Round the answer to one decimal place if necessary.

5. ______________________
Concept Development
Recall that Undefined terms are terms that do not require a definition. These terms are used as a “base” to define other terms. They serve as building blocks of other mathematical terms.
Use the image given to describe the relationships among the four terms.
On your whiteboard, in your own words define what is a “angle bisector ”? A angle bisector is ________________
______________________
CFU
*In Geometry, we have three undefined terms: point, line, and plane. The term that builds the definition of a term is placed directly below that term.

6. Solving Math Problems Solving Math Problems
Skill Development/Guided Practice (continued)
How did I/you determine what the question is asking?
How did I/you determine the math concept required?
How did I/you determine the relevant information?
How did I/you solve and interpret the problem?
How did I/you check the reasonableness of the answer?
CFU 2 1 3 4 5
Solving Math Problems
1 Determine what the question is asking.
2 Determine the math concept required.
3 Determine relevant information.
4 Solve the problem, then interpret the answer.
5 Check the reasonableness of your answer.
1. The figure shows a map of five streets that meet at Concord Circle. The measure of the angle formed by Melville Road and Emerson Avenue is 119°. The measure of the angle formed by Emerson Avenue and Thoreau Street is 135°. Hawthorne Lane bisects the angle formed by Melville Road and Emerson Avenue. Dickinson Drive bisects the angle formed by Emerson Avenue and Thoreau Street. What is the measure of the angle formed by Hawthorne Lane and Dickinson Drive? Explain your reasoning.?
*An angle bisector is a ray that divides an angle into two angles that both have the same measure.
2. A carpenter is building a rectangular bookcase with diagonal braces across the back, as shown. The carpenter knows that m   ADC is a right angle and that m  BDC is 32° greater than m  ADB. Solve an equation to find m  BDC and m  ADB.
Solving Math Problems
1 What am I trying to find?
2 What do I know about this idea?
3 What amounts do I know?
4 Solve the problem or answer the question.
5 Did I answer all parts of the question?
By the Angle Addition Postulate 
Therefore,

7. What did you learn today about how to Bisect angles and find the missing angle measurements.
SUMMARY CLOSURE
Today, I learned how to __________________
______________________________________________________________.