## Triangle and its properties-NCERT Solutions Class 7 Maths

**Class 7 Maths – Chapter 6 – Triangle and its properties ****Introduction**

A plane figure surrounded by three line segments is called a triangle. It is donated by the symbol **∆**. So if we talk about **∆ABC** it has

- Three vertices, namely
**A, B,**and**C**. - Three sides namely
**AB, BC,**and**CA**. - Three angles namely ∠
**A,**∠**B,**and ∠**C**.

A triangle has six parts – 3 sides and 3 angles.

__Types of triangle__

We know that triangle can be classified on the basis of sides and angles.

__Based on Sides__

- Scalene triangle
- Isosceles triangle
- Equilateral triangle

__Based on Angles__

- Acute angled
- Obtuse-angled
- Right angled triangle

*Maths NCERT solutions of Class 7 are available at Class 7 Maths.*

__Medians of a triangle__

The line segment joining the mid-point of a line segment **BC** of a triangle to its opposite vertex **A** is called median of the triangle.

A median connects a vertex of a triangle to the mid-point of the opposite side.

In the above triangle **ABC, AE** is the median of the side **BC**.

**CD** is the median of the side **AB**

**BF** is the median of the side** AC**

__Altitudes of a triangle__

An altitude has one endpoint at a vertex of the triangle and the other on the line containing the opposite side. Through each vertex of a triangle, an altitude can be drawn.

Below is the figure which will represent median and altitude in the single triangle.

*Watch and learn more about median and altitude – Class 7 Maths.*

__Exterior angle of a triangle and its properties__

An exterior angle of a triangle can be formed by extending the sides of a triangle at its vertex. A triangle can have three exterior angles.

*An exterior angle of a triangle is equal to the sum of its interior opposite angles.*

__Proof:-__

** Given **– Consider ∆ABC

∠ACD is an exterior angle

__To Show:-__

M ∠ACD=m ∠A +m ∠B

Through C draw CE parallel to BA

∠1= ∠X (BA is parallel to CE and AC is a transversal so the alternate angle should be equal)

∠2= ∠y (BA is parallel to CE and AD is a transversal so the corresponding angle should be equal)

∠1+ ∠2= ∠x+ ∠y

As we know ∠x+ ∠y=m ∠ACD

So, ∠1+ ∠2= ∠ACD

Hence proved

The above relation proved between an exterior angle and its two interior opposite angles are referred as the exterior angle property of a triangle.

*For examples and practice questions click on CBSE Class 7th Maths.*

## You can read more topics of **Maths NCERT Solutions Class 7**

We will discuss the angle sum property of the triangle in the next article.

Takshila Learning is setting its standards in the educational industry by providing excellent education matter and facilities to students as per their need and without putting much cost pressure on parents. Our aim is to keep our content handy and which is easily grasped by students. We offer various courses – live classes for school, CS courses, digital marketing course, and competitive exam preparation. For details visit www.takshilalearning.com

## No comments, be the first one to comment !