What is the angle sum property of a triangle?

The angle sum property of a triangle states that all the interior angles of a triangle add up to 180 degrees.

How many types of triangles are there when classified on the basis of their sides?

Based on the measure of their sides, there are 3 types of triangles: 1. Equilateral Triangle (all 3 sides are equal) 2. Isosceles Triangle (2 sides are equal) 3. Scalene Triangle (no sides are equal)

How many types of triangles are there when classified on the basis of their angles?

Based on the measure of their angles, there are 3 types of triangles: 1. Acute Triangle (all angles are less than 90º) 2. Obtuse Triangle (one angle is greater than 90º) 3. Right Triangle (one angle is 90º)

What is the formula to find the area of a triangle?

Area of a Triangle = 1/2 × Base × Height

What is Triangle? - [Definition, Facts & Example]

What is a Triangle?

In geometry, a triangle is a closed, two-dimensional shape with three straight sides. A triangle is also a polygon.

We can find the shape of a triangle in a flag, the musical instrument triangle, and a roadside signboard.

Properties of a Triangle

A triangle has three sides, three vertices, and three angles.
The sum of the three interior angles of a triangle is always 180°.
The sum of the length of two sides of a triangle is always greater than the length of the third side.
A triangle with vertices P, Q, and R is denoted as △PQR.
The area of a triangle is equal to half of the product of its base and height.

Different Types of Triangles

To classify triangles according to their angles, we measure each of its interior angles. Triangles can be classified by angles, as:

Acute Triangle

Right Triangle

Obtuse Triangle

An acute triangle has all interior angles acute (less than 90°), a right triangle has one right angle (equal to 90°) and an obtuse triangle has one obtuse angle (greater than 90°).

To classify the triangles according to their sides, we measure the length of each of its sides. Triangles can be classified by their sides, as:

Equilateral Triangle

Isosceles Triangle

Scalene Triangle

To classify triangles according to both angles and sides, we measure the interior angles and length of the sides of the triangle. Few examples of triangles classified on the basis of both angles and sides are:

Acute Equilateral Triangle

Right Isosceles Triangle

Obtuse Scalene Triangle

Fun Facts

A triangle can always be split into two right triangles, irrespective of its orientation.
Triangles are polygons with the least number of sides.

Let's sing!

Jenna loves triangles!

Tiny triangles on her blouse,

The red roof of her dollhouse,

A piece of cheese for her mouse.

Let's do it!

Instead of handing out math worksheets to your children, ask your child to observe/spot the things that are triangular in shape.

You can also give them toothpicks or straws and ask them to form all the different types of triangles using them.

Related math vocabulary-

Acute Triangle, Right Triangle, Obtuse Triangle, Equiangular Triangle, Equilateral Triangle, Isosceles Triangle, Scalene Triangle

Frequently Asked Questions

What is the angle sum property of a triangle?

The angle sum property of a triangle states that all the interior angles of a triangle add up to 180 degrees.
How many types of triangles are there when classified on the basis of their sides?

Based on the measure of their sides, there are 3 types of triangles: 1. Equilateral Triangle (all 3 sides are equal) 2. Isosceles Triangle (2 sides are equal) 3. Scalene Triangle (no sides are equal)
How many types of triangles are there when classified on the basis of their angles?

Based on the measure of their angles, there are 3 types of triangles: 1. Acute Triangle (all angles are less than 90º) 2. Obtuse Triangle (one angle is greater than 90º) 3. Right Triangle (one angle is 90º)
What is the formula to find the area of a triangle?

Area of a Triangle = 1/2 × Base × Height

Triangle - Definition with Examples