Main content

## Angle types

Current time:0:00Total duration:2:15

# Recognizing angles

CCSS Math: 4.G.A.1

## Video transcript

Look at the diagram below, then
answer the following question. What type of angle is the angle
highlighted in the green below? So it looks like
two anteaters going after an ant right over here. And this anteater is
going straight down, or at least on my
screen it looks like it's going straight down. And this anteater's going
straight to the left. And so it looks like this
one's going straight down, this one's going
straight to left. It looks like this is a right
angle or a 90-degree angle. And so if I have to pick
between any of these, it looks most like
a right angle. It looks like this is
exactly going down, and this is going
exactly to the left, that this is a
90-degree angle here. If this was an acute angle,
then the angle between them would be smaller. So maybe this top
one would be coming in from this direction
right over here. If it was obtuse, this
angle would be larger. So let's just check
our answer and try to do a few more of these. Which of the angles labeled
in the diagram below are acute angles? So just as a reminder, an acute
angle is less than 90 degrees. So let's see, A and C both
look larger than 90 degrees. But B and D both look
less than 90 degrees. So I'll go with B and D
are the acute angles here. Let's do another one of these. What type of angle is the angle
highlighted in green below? Well, this angle is
less than 90 degrees. If it was equal to 90
degrees, this thing would come out like this. So this is clearly
less than 90 degrees. This is an acute angle. Let me just do one more. This is a lot of fun. Select a symbol from
the drop-down menu to complete the
following statement. Then answer the question below. Angle A is less than 90 degrees. What type of angle is angle A? So angle A, it's
less than 90 degrees. So an angle less than 90
degrees is an acute angle. If it was exactly 90 degrees,
it would be a right angle. If it was larger
than 90 degrees, it would be an obtuse angle. So I will go with acute angle. And we got it right.