Angle types review

CCSS Math: 4.G.A.1
Review the following types of angles: acute, right, obtuse, and straight.  Identify and draw types of angles in some practice problems.  

Summary of angle sizes

Angle typeAngle size (in degrees)
AcuteBetween 00^\circ and 9090^\circ
RightExactly 9090^\circ
ObtuseBetween 9090^\circ and 180180^\circ
StraightExactly 180180^\circ

Right angles

A right angle is a 9090^\circ angle. A right angle is in the shape of a perfect corner, like the corner of a rectangular sheet of paper. Below is an example of a right angle.

Straight angles

A straight angle is a 180180^\circ angle. A straight angle looks like a straight line. Below is an example of a straight angle.

Acute angles

An acute angle is an angle whose degree measure is less than 9090^\circ. Below is an example of an acute angle.
When we compare an acute angle to a right angle\blueD{\text{right angle}}, we can see that an acute angle is less than 9090^\circ.

Obtuse angles

An obtuse angle is an angle whose degree measure is greater than 9090^\circ but less than 180180^\circ. Below is an example of an obtuse angle.
When we compare an obtuse angle to a right angle\blueD{\text{right angle}}, we can see that an obtuse angle is greater than 9090^\circ.
When we compare an obtuse angle to a straight angle\greenD{\text{straight angle}}, we can see that an obtuse angle is less than 180180^\circ.
Want to learn more about angle types? Check out this video.

Practice set 1: Identify angles

Want to try more problems like this? Check out this exercise.

Practice set 2: Angles in diagrams and images

Want to try more problems like this? Check out this exercise.

Practice set 3: Drawing angle types

Want to try more problems like this? Check out this exercise.
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