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Not to be confused with angels, angles are the pointed corners of shapes. Angles can be named three different ways.
This angle could be named any of these ways:
Look Out: when naming an angle using three letters, the vertex must always be the middle letter!
|Acute Angle||An angle less that 90°.
Lame joke: this angle is so small and a-cute!
|Obtuse Angle||An angle greater than 90°, but less than 180°.|
|Right Angle||An angle that is exactly 90°.
This is commonly denoted with a small box in the corner.
|Straight Angle||A 180° angle. |
It's - you guessed it - a straight line.
|Supplementary Angles and Linear Pairs||Angles that add up to 180°.|
are supplementary angles.
If the two angles are adjacent (next to each other) and add up to 180°, they are a linear pair.
are also a linear pair.
|Complementary Angles||Angles that add up to 90°.
|Vertical Angles||When two lines intersect, opposite angles are called "vertical angles". |
Vertical angles are congruent.
See the squiggly line over the equal sign above? This symbol means congruent. Oh, and btw, congruent angles have the same measurement.