1. A right angle is one that measures exactly 90 degrees:
Types of Angles
A right angle is one that measures exactly 90 degrees:
                                                                         
An acute angles is one that measures between 0 degrees and 90 degrees:
                                                                                              
An obtuse angle is one that measures between 90 degrees and 180 degrees:
                                                                           
A straight angle is one that measures exactly 180 degrees:
                                                                  

2. Perpendicular Lines – 2 lines that intersect and form 4 right angles.

3. Two angles whose sum is 180◦
Supplementary Angles
Two angles whose sum is 180◦ 1 2
Complimentary Angles
Two angles whose sum is 90◦

4. a pair of non-adjacent angles that are equal to each other.
Vertical Angles
a pair of non-adjacent angles that are equal to each other.
<1 = < 2
<3 = < 4 1 4 3 2

5. Parallel Lines – 2 lines in the same plane that never intersect.
Transversal - the line that cuts through the
parallel lines. a b c

6. Types of Angles
Corresponding Angles – The 2 angles located in matching corners. They are equal in measure 1 5 2 4 3 6 7 8

7. Types of Angles
Alternate Interior Angles - The 2 angles located inside the parallel lines on opposite corners. They are equal in measure. 1 5 2 4 3 6 7 8 1 5 2 4 3 6 7 8

8. Types of Angles
Alternate Exterior Angles - the 2 angles located outside the parallel lines on opposite corners. They are equal in measure. 1 5 2 4 3 6 7 8

9. Types of Angles
Vertical Angles - The 2 angles opposite each other when 2 lines intersect. They are equal in measure. 1 5 2 4 3 6 7 8

10. Types of Angles
Supplementary Angles - The 2 angles that make a straight line. They equal 180o. 1 5 2 4 3 6 7 8

11. Vocabulary
English
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Chinese
Corresponds
Corresponder a
Corresponde 对应
Proportional
proporcional
Proporcional
按比例
Congruent
congruente
congruentes 全等
Similar
parecido
Semelhantes 类似
alternate (opposite)
alternar
suplente (oposto)
备用（外）
Interior (inside)
Interior
Interior (para dentro) 内部
Exterior (outside)
exterior 外观