Angles and Triangles

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Presented By, Krishna kumari and Z,verghese

KendriyaVidyalaya,

I N S Hamla.

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Contents

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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

Isosceles Triangle

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

A

B

C

Equilateral Triangle

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

A

B

C

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

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

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

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

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.

Scalene Triangles

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

A

B

C

Isosceles Triangle

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

A

B

C

Equilateral Triangle

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

A

B

C

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

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

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

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

Triangle Properties:Isosceles

• Property1: the angles opposite to equal sides are equal.

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• Converse: the sides opposite to equal angles are equal.

A

B

C

P

Q

R