Two rays that meet and form a square corner form a right angle. Right angles measure 90 degrees, or 90°.
Right angles are often identified with a small square inside the right angle.
Example:
∠EFG is formed by ray FE and ray FG. Ray FE extends vertically, and ray FG extends horizontally, meeting at point F to form a right angle (90°).
This right angle is identified by a small square placed at the vertex.
Look at the angles below. Which is a right angle?
∠LOG is a right angle.
Finding Right Angles in the Real World
Did you know that angles are all around us? Many everyday objects form right angles without us even realizing it! Unlike acute angles, which are smaller and narrow, or obtuse angles, which are wider, right angles create a perfect 90° corner.
Here are some fun examples:
- The corner of a window – The edges of most windows meet at a perfect 90° angle.
- The hands of a clock at 3:00 – The hour and minute hands form a right angle when the time is exactly 3:00 (or 9:00!).
- A laptop that is fully opened – When opened to form a perfect L-shape, the base and screen create a 90° angle.
Since right angles measure exactly 90°, you can find them in many places. Can you spot any other objects with right angles around your home or classroom?
Measuring a Right Angle with a Protractor
Angles are measured in degrees, like temperature. A small circle above the angle measurement means “degrees.”
A right angle always measures exactly 90°.
You can measure angles using a tool called a protractor.
To measure ∠JAM, follow these steps:
- Line up ray AJ with the straight bottom edge (0° line) of the protractor.
- Find where ray AM points on the protractor’s scale.
- Notice that AM passes through 90°, confirming that ∠JAM is a right angle.
Tip: Right angles are easy to spot because they always have a small square at the vertex instead of just a curve!
Practice Problems
Which is a right angle?
What is the measure of a right angle?
Which of the following objects most likely contains a right angle?
A right angle is always greater than 90°.
A right angle is exactly 90°, not greater than 90°.
