This document discusses triangles and their properties. It defines a triangle as a shape with three connected line segments and three vertices. The key properties discussed are: 1) The sum of the three interior angles of any triangle is always 180 degrees. 2) For a shape to be a triangle, the length of any one side must be less than the sum of the other two sides. 3) Triangles can be categorized based on the lengths of their sides (scalene, isosceles, equilateral) or degrees of their angles (acute, right, obtuse).

1. Triangles
Class V
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2. I can be big or small.
You can find me all around.
I am made up of three
connected lines.
I have three vertices
I have three angles
Who am I?
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3. 3

4. I am a Triangle
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5. Parts of Triangle
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6. Worksheet 1 from DAV Book
to be done.
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7. Note that
• the unit of measure of an angle is called DEGREE.
Recall
• Angle on a straight line is a straight angle and it
measures 1800 .
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8. Angle Sum Property of Triangle
Property: Sum of the three angles of a triangle
is always 1800
To be done by activity method in class room
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9. Worksheet 2 from DAV Book
to be done.
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10. Side inequality Property of
Triangle
To be done by activity method in class room
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11. Lets take an example where the sides are
given to be 10 cm, 4 cm and 3 cm. check if it
is possible to make a triangle with given sides
or not.
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12. Worksheet 3 from DAV Book
to be done.
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13. Types of Triangle
On the basis of sides On the basis of angles
• Scalene triangle
• Isosceles triangle
• Equilateral triangle
• Acute angled triangle
• Right angled triangle
• Obtuse angled triangle
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14. Types of Triangle on the
basis of sides
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15. Scalene Triangle
A triangle in which length of all three sides is
different is called a scalene triangle
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16. Isosceles Triangle
A triangle in which length of any two sides is same
is called an isosceles triangle
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17. Equilateral Triangle
A triangle in which length of all three sides is same
is called an equilateral triangle
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18. Types of Triangle on the
basis of angles
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19. Acute angled Triangle
A triangle in which all three angles are acute ( <900)
is called acute angled triangle.
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20. Right angled Triangle
A triangle in which one angle is right ( = 900) is
called right angled triangle.
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21. Obtuse angled Triangle
A triangle in which exactly one angle is obtuse ( > 900)
is called obtuse angled triangle.
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22. Worksheet 4 from DAV Book
to be done.
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23. Thanks!!!
Prepared by: Richa Bhardwaj
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