Right Angles
What is a right angle?
When an angle between two lines is exactly 90° it is called a right angle. Two lines are perpendicular to each other.
1. Study the marked angles on the objects below.
![model diagram](/images/notes/P3PPL_Perpendicular_Parallel_Lines_1.png)
Each of the marked angles is a right angle.
2. Which of the angles below is smaller than a right angle?
Which one is greater than a right angle?
Which one is a right angle?
![model diagram](/images/notes/P3PP_PP_2.png)
Let's use a ruler to check for right angles.
3. How many right angles are there in each figure below?
![model diagram](/images/notes/P3PP_PP_3.png)
Figure A:
Figure A has 1 right angle.
Figure B:
Figure B has 4 right angles.
Figure C:
Figure C has 2 right angles.
![](/images/notes/P3PP_PP_3a.png)
Figure B:
![](/images/notes/P3PP_PP_3b.png)
Figure C:
![](/images/notes/P3PP_PP_3c.png)