- Books Name
- CBSE Class 7 Mathematics Book

- Publication
- Param Publication

- Course
- CBSE Class 7

- Subject
- Mathmatics

**Triangle**

A triangle is a closed figure made by three line segments. It has three vertices, three sides and three angles.

A triangle ABC is given having three vertices A, B, C and three sides AB, BC, CA and three angles are *∠*ABC, *∠* BCA, *∠*CAB.

**Classification of triangles:**

1. With respect to angles are:

(a) Acute-angled triangles

(b) Obtuse-angled triangles

(c) Right-angled traingles

**(a) Acute-angled triangles**

** **

A triangle in which measurement of each of the three angles are less than 90°.

**(b) Obtuse-angled triangle :**

A triangle in which one angle is obtuse angle i.e. greater than 90° but less then 180°.

**(c) Right-angled triangle:**

A triangle in which one angle is exactly 90°.

• The side opposite to the right angle is called the hypotenuse.

• The other two sides are called as the legs of the right-angled triangle (or base and perpendicular).

• In the given figure AC is the hypotenuse and AB and BC are the legs of DABC.