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Angles and Triangles

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Presented By, Krishna kumari and Z,verghese

KendriyaVidyalaya,

I N S Hamla.

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WE CAN DRAW A LINE SEGMENT ON A PAPER AND IT HAS DEFINITE LENGTH�A RAY AND LINE HAVE NO DEFINITE LENGTH

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TWO RAYS AND LINE SEGMENTS WITH THE COMMON END POINT FORM AN ANGLE

A WHERE TWO END POINTS MEET IS CALLED VERTEX

AND LINE SEGMENTS ARE CALLED ARMS

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ACUTE ANGLE

A

B

C

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RIGHT ANGLE

A

B

C

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OBTUSE ANGLE

A

B

C

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Triangles-Introduction

  • Definition: A plane figure bound by three lines in a plane is called a triangle.a triangle has 6 parts.(3sides & 3angles).
  • Here,AB,AC&BC are the sides,A,B & C are points.

A

B

C

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Triangle

Definition: A triangle, HAS THREE LINE SEGM ENTS ,THR EE VERTIC E S AN D THR EE ANGLES

A

B

C

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Types Of Triangles

On the basis of sides:

1. Scalene triangles

2. Isosceles triangles

3. Equilateral triangles.

On the basis of angles:

4.Acute triangles

5.Right triangles

6.Obtuse triangles.

An equilateral triangle is an isosceles triangle but the converse is not true.

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Scalene Triangles

  • Definition: A triangle,no two of whose sides are equal, is called a scalene triangle. E.g..

A

B

C

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Isosceles Triangle

Definition: A triangle, two of whose sides are equal, is called an isosceles triangle.e.g.

A

B

C

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Equilateral Triangle

  • Definition: a triangle whose all sides are equal, is called an equilateral triangle.e.g.

A

B

C

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Acute triangle

  • Definition:A triangle each of whose angles is acute is called an acute angled triangle or simply acute triangle.e.g.

A

B

C

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Right Triangle

  • Definition: A triangle with one angle a right angle is called a right angled triangle or simply right triangle.e.g.

A

B

C

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Obtuse triangle

  • Definition: A triangle with one angle an obtuse angle is known as obtuse angled triangle or simply obtuse triangle.e.g.

A

B

C

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Triangle properties-1

  • Property 1:the sum of the three angles in a triangle is 180 degrees.

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  • Property 2:if a side of a triangle is produced then the exterior angle so formed is equal to the sum of the two interior opposite angles.

A

B

C

Here, angle A+angle B+angle C=180 degrees.

A

B

C

D

Here,angle ACD = angle A+angle B