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Hi everyone!
Today we're going to talk about angles.
An angle is the amount of turn, or space,
between two lines that meet each other.
When two lines meet at a point, or vertex,
an angle is formed.
The two lines are called the arms of the angle.
Angles are measured in degrees, which is shown
by this symbol.
A complete turn, also known as a full rotation,
all the way back to the place it started,
is 360 degrees.
One half of a turn, which forms a straight
line, is 180 degrees.
One quarter of a turn is 90 degrees.
This is called a right angle.
There are three other types of angles: acute,
obtuse, and reflex angles.
An acute angle is one that is less than 90
degrees.
An obtuse angle is one that is more than 90
degrees, but less than 180 degrees.
A reflex angle is one that is greater than
180 degrees.
Some angles may be added together to get one
of the important angles we talked about earlier.
Complementary angles are two angles that add
up to a 90 degree angle.
Supplementary angles are two angles that add
up to a 180 degree angle.
Two angles that add up to make a full circle
or 360 degree angle can be called either explementary
or conjugate angles.
Some other fun facts about how angles add
up include that all the angles inside a triangle
will always add up to 180 degrees, and all
the angles around the point where lines intersect
will always add up to 360 degrees.
Angles are usually measured using protractors.
Protractors have markings on them, similar
to rulers, but instead of inches or centimeters
it measures in degrees.
If you don't have a protractor to measure
with, you can estimate how big it is as long
as you remember what a 90 degree angle, 180
degree angle, and 360 degree angle look like.
I hope this helped you understand all about
angles today.
Good-bye till next time!
