Today's Goals:

​Classify angles.

Identify adjacent and vertical angles.

Angles are measured with DEGREES

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The measurement is usually written INSIDE the corner it applies to.​

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NOT USED FOR ANGLES:​

• inches​

• feet

• centimeters​

• millimeters

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Measuring Angles

Naming Angles

• Can be named using a number:

  • ∠1   means "ANGLE 1"

• Can be named using a single letter:

  • ∠A  means "ANGLE A" (not shown)

• Can be named using three letters (see next slide)

• ​m∠3  - means "MEASURE/SIZE OF "ANGLE 3"

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This symbol ∠  is NOT "less than"  that's this symbol:  <​

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​The MIDDLE LETTER is always a CORNER

Find the angle by following the letters:

angle ∠ABC  is the entire L shape

• ∠ABD  is the same as ∠DBA  

  • It's also the same as ∠1  

• ∠DBC  is the same as ∠CBD 

  • It's also the same as  ∠2​

3 LETTERS

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• They're exactly 90^o

• ​They look like a perfect T or L

• See a square in the corner? (right angle!)

  • DO NOT ASSUME an angle is exactly 90^o

  • >> unless the picture or directions say so​

Right Angles

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Adjacent means "NEXT TO"​

Adjacent angles SHARE A WALL

Adjacent angles also SHARE A CORNER/VERTEX

• ∠Q  and  ∠R  are adjacent

• ∠Q  and  ∠T  are adjacent

• ∠Q  and  ∠S  are not adjacent (they're "across the street" neighbors!)

Adjacent Angles

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Vertical Angles are opposite angles

Vertical Angles are formed by the intersection of two lines.

Vertical angles are congruent angles, meaning they have the same measure.

• ∠Q  and  ∠S  are vertical

• ∠T  and  ∠R  are vertical

Vertical Angles

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