http://www.moomoomath.com/Classifying-Angles.html
In Geometry there are four main angles you will be working with. They are an acute angle, obtuse angle, right angle, and straight angle. Video gives a quick summary of each angle.
Test your knowledge with this video naming angles
Up first are triangles that are classified by the length of their sides
Scalene triangle
Three different side lengths
Three different angle measures
Isosceles triangle
At least two congruent sides
At least two congruent angles
Equilateral triangle
Three congruent sides
Three congruent angles The angle measure equals 60 degrees
Triangles can also be classified by their angles.
There are three angles often associated with triangles
Acute angles are less than 90 degrees
Right angles are exactly 90 degrees
Obtuse is greater than 90 degrees
All triangles have two acute angles and the third angle determines the type of
Triangle you have.
Acute triangle
Triangle with three angles that measure less than 90 degrees
Obtuse triangle
Triangle with one angle greater than 90 degrees
Right triangle
Triangle with one right angle ( 90 degrees)
The other two angles are complementary
First, are triangles that are classified by the length of their sides
Scalene triangle
Three different side lengths
Three different angle measures
Isosceles triangle
At least two congruent sides
At least two congruent angles
Equilateral triangle
Three congruent sides
Three congruent angles The angle measure equals 60 degrees
Triangles can also be classified by their angles.
There are three angles often associated with triangles
Acute angles are less than 90 degrees
Right angles are exactly 90 degrees
Obtuse is greater than 90 degrees
All triangles have two acute angles and the third angle determines the type of
Triangle you have.
Acute triangle
Triangle with three angles that measure less than 90 degrees
Obtuse triangle
Triangle with one angle greater than 90 degrees
Right triangle
Triangle with one right angle ( 90 degrees)
The other two angles are complementaryTranscript
Today we are going to look at angles. The first angle we are going to look at is the ninety-degree angle. That makes an L shape and the symbol is a little square box in the corner. Then we have what is called a straight angle which is straight across without an actual angle. I think of it as just a straight line. Then you have an angle that falls smaller than ninety degrees. That one is an acute angle, and then you have an angle that is larger than ninety, but less than straight and that is an obtuse angle so let's label those. This first one is ninety, and that is kind of your reference and you always want to be familiar with a ninety degree in order to see if an angle is smaller than it. That one would be an acute angle because it is less than ninety and this one is larger than ninety and you can sketch in your L if you want to in order to compare it, and that one is greater so it is obtuse and then a straight line is one hundred and eighty because it is kind of like two L's put together and ninety and ninety is one eighty so this is your straight angle. So you are always comparing to your ninety-degree angle or your right angle. So that's how angles classify. So let's look at the rules. An acute angle is less than ninety degrees. A right angle is equal to ninety degrees and it is your reference angle. An obtuse angle is greater than ninety degrees and a straight angle which is equal to one hundred and eighty degrees. You can also use a protractor to measure an angle and when you use a protractor take the dot and line it up with the vertex. What is the vertex? It is the corner of the angle. Line it up, read it from the bottom up. This is how you classify angles.
-~-~~-~~~-~~-~-
Please watch: "Study Skills Teacher's Secret Guide to your Best Grades"
https://www.youtube.com/watch?v=f3bsg8gaSbw
-~-~~-~~~-~~-~-
You may also enjoy, Naming angles
https://www.youtube.com/watch?v=FMCA9_lqDAo&t=49s