Download 1 - Hartland High School

1.4 Measure and Classify Angles
Goal • Name, measure, and classify angles.
Draw 2 rays with the same endpoint. LABEL the rays.
Two rays that have the same endpoint form an ___________________________.
The RAYS are the _______________ of the angle. In the angle above, the sides are _____ and _____.
The COMMON ENDPOINT is the ___________ of the angle. In the angle above, the vertex is _____.
An angle is named using points on it. Names for the above angle: ________ , ________ , _______ ,
_______.
Example 1: Name the three angles in the diagram.
The MEASURE OF AN ANGLE is written in units called ___________________________.
We use a _______________________________ to measure angles.
Example 2: Use a protractor to measure  BAC and Q below. Use proper notation when you give
each measure.
B•
A
C
•
Q
Angles are classified by their measure:
Acute Angle
Obtuse Angle
Right Angle
Straight Angle
1.4 Measure and Classify Angles
POSTULATE 4: ANGLE ADDITION POSTULATE
If P is in the interior of RST, then
mRST = mRSP+ mPST.
Example 3: Given that mGFJ = 155°, find mGFH and mHFJ.
Example 4: Identify all pairs of congruent angles in the diagram. If mP = 120°, what is mN?
A ray that divides an angle into two congruent angles is an __________________________________.
Example 5: In the diagram at the right, WY bisects XWZ, and mXWY = 29°. Find m XWZ.
Checkpoint Complete the following exercises.
1. Name all the angles in the diagram at the right. 2. What type of angles do the x-axis and y-axis
form in a coordinate plane?
3. Given that VRS is a right angle, find
mVRT and TRS.
4. Identify all pairs of congruent angles
in the diagram. If mB = 135°, what is mD?