Math Doubts

Interior angles of a Triangle

An angle that is formed inside a triangle by the intersection of its sides, is called an interior angle of a triangle.

Introduction

interior angles of triangle

A triangle is formed by connecting the endpoints of three line segments as a closed geometric shape. The intersection of every two sides of a triangle forms an angle internally. Hence, the angle is called an interior angle of triangle. It is also called as an internal angle of a triangle.

In a triangle, the three line segments are intersected at three locations on a plane. Hence, three interior or internal angles are formed inside a triangle.

Example

For understanding the concept of internal angles of a triangle, let’s construct a triangle geometrically.

formation of interior angles of triangle
  1. Take three line segments of any length.
  2. Form a closed geometric shape by connecting an endpoint of a line segment to an endpoint of another line segment. Thus, a triangle is formed geometrically.
  3. The connection of every two line segments inside a triangle forms an angle. The angle is called an interior or internal angle. There are three interior angles formed in a triangle.

Thus, a triangle, denoted by $\Delta MLN$ is formed geometrically.

In this triangle, $\angle LMN$, $\angle MLN$ and $LNM$ are called interior or internal angles of the triangle.

internal angles of triangle

In this example, the internal angles $\angle LMN$, $\angle MLN$ and $LNM$ are unknown but they can be measured by a protractor.

The interior angles in $\Delta MLN$ are measured that

$(1).\,\,\,$ $LMN \,=\, 42^°$

$(2).\,\,\,$ $MLN \,=\, 56^°$

$(3).\,\,\,$ $LNM \,=\, 82^°$

Geometrically, the sum of interior angles in a triangle is equal to $180^°$.

Math Doubts

A best free mathematics education website for students, teachers and researchers.

Maths Topics

Learn each topic of the mathematics easily with understandable proofs and visual animation graphics.

Maths Problems

Learn how to solve the math problems in different methods with understandable steps and worksheets on every concept for your practice.

Learn solutions

Subscribe us

You can get the latest updates from us by following to our official page of Math Doubts in one of your favourite social media sites.

Copyright © 2012 - 2022 Math Doubts, All Rights Reserved