The document defines and describes different types of triangles based on their sides and interior angles. It discusses equilateral triangles which have three equal sides and three equal interior angles of 60 degrees. It discusses isosceles triangles which have two equal sides and can be oriented in two ways. It discusses right triangles which have one 90 degree interior angle.

2. The Definition of Triangles
C
Triangle is plane figure
which is bordered by three
lines (sides) A
B
Vertex
Vertex :: A, B, C
A, B, C
Side
Side :: AB, AC, BD
AB, AC, BD

3. Triangles Based on Relative
Length of Their Sides

4. Equirateral Triangle
Equilateral triangle is a triangle which has three
equals sides.

5. Isosceles triangle
Isosceles triangle is a triangle which has two
equals sides.

6. Scalene Triangle
Scalene triangle is a triangle which has no equals
sides.

7. Triangle Based on the Measure
of Their Interior Angles

8. Acute Triangles
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9. Obtuse Triangles
An obtuse triangle is a triangle that has
one obtuse angle.

10. Right Triangles
A right-angled triangle is a triangle that has one
90º angle.
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11. Based on its Sides and the
Measure of
Interior Angle

12. Right Isosceles Triangle
Right isosceles triangle is a triangle that has
one 90º angle and two equal sides.
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13. Obtuse Isosceles Triangle
Obtuse Isosceles Triangle is a triangle that
has one obtuse angle and two equal sides.
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14. Acute Isosceles Triangle
Acute Isosceles Triangle is a triangle that
has one acute angle and two equal sides.
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15. Obtuse Scalene Triangle
Obtuse Scalene Triangle is a that has one
obtuse angle and no equal sides
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16. Acute Scalene Triangle
Acute Scalene Triangle is a triangle that has
one acute angle and has no equal sides
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18. Equilateral Triangles
All of sides are equal in
length
All of angles are equal in C
measure
Can fill its frame in 6 ways
The sum of all angles is
B
180º
Has three axes of symmetry
180º

19. Isosceles
 Has two equal sides
 Can fill its frame in 2
ways
 All of its angles are acute
angle
 Has a pair of same angle
 Has an axis of symmetry

20. Right Triangle
 Has a right angle
 Has 2 acute angles
 Can fill its frame in a
way
 We can form some
plane figures such
as...
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21. Here are...
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22. Angle in Triangle
 The sum of all angles
in triangle is 180º

23. Angle in Triangle
Exterior angle is formed by
Exterior angle is formed by
The measure of an one side and the extension
one side and the extension
exterior angle of a of another side of angle
of another side of angle
triangle is equal to
the sum of two
interior angles which Exterior Angle
are not
supplementary to the
exterior angle.
Interior Angle
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24. Perimeter of Triangle
Sum of all the sides in triangle
Example C
10 cm + 6 cm + 8 cm
= 24 cm
8 cm 10 cm
A B
6 cm
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25. Area of Triangle
A
= 108 cm : 2 cm = 54 cm2 12 cm 15 cm
B C
9 cm

26. Thank you for
your attention.
See You