Triangles

Triangles

A triangle is just a shape with three straight lines joined together like a slice of pizza or the roof of a small house. Triangles are three-sided polygon that consists of three edges and three vertices. This means it has three sides, three corners, and three angles inside it.

The biggest thing to remember is that if you add all three corners inside any triangle, they must give you 180 degrees. The most important property of a triangle is that the sum of the internal angles of a triangle is equal to 180o. This 180 degrees rule is the same for every single triangle in the world.

We have 6 different types of triangles that we will look at soon. Many big topics in math, like how to find the side of a building or how to measure distances, use the rules of triangles.

Properties of Triangle

The sum of angles of a triangle is always 180o.

The exterior angles of a triangle always add up to 360o.

The sum of the lengths of any two sides of a triangle is greater than the length of the third side. Similarly, the difference between the lengths of any two sides of a triangle is less than the length of the third side.

The shortest side is always opposite the smallest interior angle. Similarly, the longest side is always opposite the largest interior angle.

Types of Triangles

We group triangles by looking at how long their sides are and how wide their corners are.

Triangles based on sides

Scalene triangle: This is a triangle where all three sides have different lengths, like a three-way junction where no road is the same length.

Isosceles triangle: This triangle has two sides that are exactly the same length, just like the two sides of a ladder.

Equilateral triangle: In this one, all three sides are perfectly equal, like a balanced signpost.

Triangles based on angles

Acute triangle: This is a triangle where all the three angles inside are small, less than 90 degrees.

Right angle triangle: This triangle has one corner that stands straight up like the corner of a textbook, which is exactly 90 degrees.

Obtuse triangle: This triangle has one very wide corner that is more than 90 degrees.