Angles of a triangle

Aim

To show that the three angles of a triangle add up to 180°.

Apparatus

• Protractor
• A paper triangle
• Scissors

Method

1. Draw a triangle.
2. Measure each angle with the protractor.
3. Record them and add them up.
4. Tear off the three corners and place them side by side: they form a straight line.
5. Repeat for at least 4 triangles.

Conclusion

The angles always add up to 180° (small differences come from measuring), so the three corners make a straight line.