The document outlines the fundamental elements and properties of triangles, including definitions of sides, angles, and vertices. It categorizes triangles based on sides (equilateral, isosceles, scalene) and angles (acute, right-angled, obtuse) and discusses key properties such as the angle sum property (180 degrees) and side length relationships. A review exercise is provided to reinforce understanding, along with answer keys.

1. Class V
Kavita Grover
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2. Elements of a Triangle
Sides
Side AB
Side BC
Side CA
Angles
ABC
ACB
BAC
Vertices
A,B,C
A
B C
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3. Types
of Triangles
Based on
sides
Based on
angles
Equilatera
l
Isosceles
Scalene Acute
Right
-angled
Obtuse
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4. Review Exercise
Tick the correct option.
1) A triangle is formed by joining
a) 3 points
b) 3 collinear points
c) 3 lines
d) 3 non collinear points
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6. 3) How will you denote a side
AB of a triangle
a) Line AB
b) AB
c) AB
d) Side AB
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7. 4) The given triangle
is
a) Obtuse angle
triangle
b) Scalene triangle
c) Isosceles triangle
d) Acute angle
triangle
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8. Answers
1) b
2) c
3) b
4) d
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10. Angle sum property of a Triangle
The sum of the angles of a triangle is 180˚.
A
B C
A+ B+ C = 180˚
A
B
C
A+ B+ C= 180˚
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11. Side property of a Triangle
The sum of the lengths
of any two sides is
always greater than the
length of the third side .
Side AB= 5cm
Side BC= 5cm
Side CA= 5 cm
AB+BC >CA
5cm+5cm >5cm
10 cm>5cm
BC+CA>AB
5cm+5cm >5cm
10cm>5cm
A
B C
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12. Side AB=4.5cm
Side BC=7cm
Side CA=5cm
Side AB+BC>AC
4.5cm+7cm>5cm
11.5cm>5cm
A
B
C
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