1. ©2010 G Dear – Not to be sold/Free to use
Stage 4
Years 7 & 8
Triangles
Types of
Triangles
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©2010 G Dear – Not to be sold/Free to use

2. Triangle Classification (1/6)
Triangles are classified based on their …
Angles
or Sides
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Acute-angled
Equilateral
Three acute Angles
Three equal sides.
Right-Angled
Isosceles
One right angle.
Two equal sides
Obtuse angled
Scalene
One obtuse angle.
No equal sides.
End of Slide

3. Triangle Classification (2/6)
Use an Angle and Side Name
for each triangle.
Angle Side
Acute
angled
Equilateral
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4. Triangle Classification (3/6)
Use an Angle and Side Name
for each triangle.
Angle Side
Right
angled
Scalene
End of Slide

5. Triangle Classification (4/6)
Use an Angle and Side Name
for each triangle.
Angle Side
Obtuse
angled
Scalene
End of Slide

6. Triangle Classification (5/6)
Use an Angle and Side Name
for each triangle. θo
Angle Side
Acute
Angled
Isosceles
End of Slide

7. Triangle Classification (6/6)
Use an Angle and Side Name
for each triangle.
Angle Side αo βo γo
Obtuse
Angled
Scalene
End of Slide

8. Angle Classification (1a/6)
Acute Angled Triangle
All angles are acute.
That is < 90o.
End of Slide

9. Angle Classification (1b/6)
Right Angled Triangle
One angle is a right-angle.
That is = 90o.
End of Slide

10. Angle Classification (1c/6)
Obtuse Angled Triangle
One angle is an obtuse-angle.
That is > 90o.
End of Slide

11. Side Classification (1d/6)
Equilateral Triangle
60o
60o
60o
Three equal length sides.
Three equal 60o angles.
End of Slide

12. Side Classification (1e/6)
Isosceles Triangle θo θo
Two equal length sides.
Two equal angles.
End of Slide

13. Side Classification (1f/6)
Scalene Triangle βo γo αo
No equal length sides.
No equal angles.
End of Slide