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ANGLES, ANGLES, ANGLES. Naming Angles Measuring Angles Classifying Angles The Angle Addition Postulate. What is an angle?. An angle is formed by two rays with a common endpoint called a vertex. CD and CE are the rays that form the sides of the angle. C is the common
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ANGLES, ANGLES, ANGLES Naming Angles Measuring Angles Classifying Angles The Angle Addition Postulate
What is an angle? An angle is formed by two rays with a common endpoint called a vertex. CD and CE are the rays that form the sides of the angle. C is the common endpoint, or vertex. D C - vertex E
NAMING ANGLES There are four different ways to name an angle: #1: -by its vertex with in front of the capital letter D This is C. C E
NAMING ANGLES There are four different ways to name an angle: #2: -by a number placed inside the angle with in front of the number D This is 3. 3 C E
NAMING ANGLES There are four different ways to name an angle: #3: -by three letters - a point on one of the rays followed by the vertex of the angle followed by a point on the other ray with in front the three capital letters. This is DCE or ECD. D C E
NAMING ANGLES There are four different ways to name an angle: #4: -by a lower case letter placed inside the angle with in front of the lower case letter. This is a. D a C E
NAMING ANGLES Click on the correct name for the angle shown. D E TEJ d T JTE J etj
Try Again! Think about capital letters and lower case letters. Think about what the middle letter should be.
WHITE NOTE CARD: ANGLES Formed by two rays with a common endpoint called a vertex. BC and BG are the rays, B is the vertex Named by: - the vertex (a capital letter) B - a number placed inside the angle 8 - three capital letters - a point on one ray followed by the vertex followed by a point CBG on the other ray; vertex always in the middle GBC - a lower case letter placed in side the angle All of these start with . C 8 B G
ANGLE MEASURE Angles are measured in degrees using a protractor. The protractor is used to measure the opening between the two rays that make up the angle.
ANGLE CLASSIFICATION Angles can be classified in four different ways: Acute angles - angles that measure less than 90º Right angles - angles that measure 90º Obtuse angles - angles that have a measure greater than 90º but less than 180º Straight angles - angles that measure 180º
True or False - Click true or false next to each statement. TRUE / FALSE - All right angles are congruent. TRUE / FALSE - All obtuse angles are congruent. TRUE / FALSE - An obtuse angle and an acute angle could be congruent. TRUE / FALSE - Three acute angles could be congruent. Continue – all finished with the True / False questions.
NO - READ THE STATEMENT AGAIN.
WHITE NOTE CARD: ANGLE CLASSIFICATION Angles can be classified in four different ways: Acute angles - angles that measure less than 90º Right angles - angles that measure 90º Obtuse angles - angles that have a measure greater than 90º but less than 180º Straight angles - angles that measure 180º
ANGLE ADDITION POSTULATE If R is in the interior of PQS, then m PQR + m RQS = m PQS. P R S Q
ANGLE ADDITION POSTULATE If R is in the interior of PQS, then mPQR + m RQS = m PQS. So, if R is in the interior of the big angle, then the sum of the measures of the two smaller angles will equal that big angle. P R S Q
ANGLE ADDITION POSTULATE If R is NOT in the interior of PQS, then mPQR + m RQSm PQS. R P S Q
ANGLE ADDITION POSTULATE If mPQR + m RQS = m PQS, thenR is in the interior of PQS. What does this mean? Think about the second part of the Segment Addition Postulate.
COLORED NOTE CARD ANGLE ADDITION POSTULATE If R is in the interior of PQS, then m PQR + m RQS = m PQS. If m PQR + m RQS = m PQS, then R is in the interior of PQS. R P S Q