Right angles
A right angle is a special corner — when two lines meet perfectly straight up to each other. The corner of a sheet of paper is a right angle. So is the corner of a window, a door, a book.
A right angle is 90°.
How to recognise one
- Take a piece of paper. The corner is a perfect right angle.
- Place the paper corner against the corner of the shape you're checking.
- If the two edges line up exactly, it's a right angle.
Right angles in shapes
| Shape | Right angles |
| Square | 4 |
| Rectangle | 4 |
| Right triangle | 1 |
| Equilateral triangle | 0 |
| Regular pentagon | 0 |
L-shape and other "corners in/out"
Look at this L-shape:
.███.
.███.
.█████
.█████It has 6 right angles: 3 outer + 3 inner corners.
When the shape goes "in" — that inner corner is also a right angle (just facing the other way).
Try it
Summary
- Right angle = 90° = corner of a sheet of paper.
- Squares and rectangles have 4 right angles.
- Right triangle has 1.
- L-shapes have several — count both outer and inner corners.