| Angles
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Angles
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Students should
be able to:
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| What
is an angle?
When
two rays share an endpoint they form an angle.
The point where the rays intersect is called the vertex
of the angle. The two rays are called the sides
of the angle.
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| How
do you measure an angle?
We measure the size
of an angle by looking at how much the two sides move, or
rotate, away from each other. As you can see below,
the sides rotate on the vertex.
The unit of measure we use to
show how much the sides have rotated is the degree
(º). In the mini-movie below you can see that the
angle rotates to a stop at four different measures:
- 45º - an angle that rotates
less than 90º. Also called an acute angle.
- 90º - an angle formed when
the rays are perpendicular. Also called a right angle.
- 135º - an angle that rotates
more than 90º. Also called an obtuse angle.
- 180º - also called a straight
angle.
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The angles above are just examples.
Angles can actually be any size and
can face any direction. We group angles into three types, based
on the size of their rotation. Click on any of the links below each
angle to read about each one.
Everything
Geometry
The Basics| Classifying
Quadrilaterals | Classifying
Triangles
Area
& Perimeter | Angles
| Circles
|
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