1. Constructing specific triangles
with scale and compass

2. drawing an arc
center
radius 2

3. drawing an arc spiky end of compass pencil end of compass
You have to draw with the compass
spread this much apart

4. Side-Side-Side (SSS)
3rd side
2nd side
hypotenuse = base

5. Side-Side-Side (SSS) Why?
Which 3 sides make it impossible to draw a triangle?
Why?
If 2 sides are equal?
If all sides are equal?
Try and see!

6. Side-Angle-Side (SAS)
3rd side
smaller side
angle = given angle
larger side = base

7. Side-Angle-Side (SAS)
What angle makes it impossible to draw a triangle?
Why?
Can you draw if the sides are equal?
Try and see!

8. Angle-Side-Angle (ASA)
2nd angle
1st angle
side = base

9. Angle-Side-Angle (ASA)
Which pair of angles make it impossible to draw a triangle?
Why?
Can you draw if the angles are equal?
Try and see!

10. Right angle-Hypotenuse-Side (RHS)
larger side = hypotenuse
smaller side = base

11. Right angle-Hypotenuse-Side (RHS)
Can the smaller side be hypotenuse?
Try and see!

12. Right angle-Hypotenuse-Angle (RHA)
angle = given angle
side = hypotenuse

13. Right angle-Hypotenuse-Angle (RHA)
Can you draw if the angle is not acute?
Why?

14. Angle-Angle-Side (AAS)
external angle =
1st angle +
2nd angle
1st angle
side = base

15. Angle-Angle-Side (AAS)
Which pair of angles make it impossible to draw a triangle?
Why?
Can you draw if the angles are equal?
Try and see!

16. Side-Side-Angle (SSA)
2nd side
1st side
angle = given angle

17. Side-Side-Angle (SSA)
Can you start with the larger side?
What happens if the sides are equal?
Try and see!

18. Side-Side-Angle (SSA)
2nd side
1st side
acute
angle = given angle

19. Side-Side-Angle (SSA)
Can you draw if the smaller side is very small?
What is the minimum length of smaller side to make a triangle possible?
What happens if the sides are equal?
Can you start with the smaller side?
Think and say!
Try and see!