VannKit Geometry - Triangles

Triangles

Review: Activity 1- Points, Lines and Angles

About Triangles

A triangle has three straight sides that connect.
The length of the sides of a triangle can vary but the length of the largest side can’t be equal or greater to the sum of the other two sides.
In addition, a triangle has three interior angles, and the sum of those three angles is always 180 degrees. This is true for all triangles,
There are six types main types of triangles.

Triangle inequality,

Given a triangle with sides a, b, and c, where c is the bigger than both a and b.

that is c ≥ b, c ≥ a

Then the sum of any two sides is greater than or equal to the third side;

a + b ≥ c.

Review: Activity 2: The Triangle Inequality Theorem

Review: Activity 3- Triangle Sum Theory

Different Types of Triangles

There are six basic types of triangles, and they fall into two groups of three.

Group 1: triangles that are categorized by the measure of their largest angle. These are the

acute,
right, and
obtuse triangles

Group 2: triangles that are categorized by how many of the sides have the same length. Here are three triangles with the lengths of the sides included.

Group 1: triangles categorized by the largest angle

Acute Triangle: The largest angle in the acute triangle is less than 90 degrees.

Right Triangle: The largest angle is exactly 90 degrees.

Obtuse Triangle: The largest angle is greater than 90 degrees.

Group 2: triangles categorized the number of sides with the same lengths

Equilateral Triangle

all three sides are the same length

all three angles are equal measure 60 degrees.

Isosceles Triangle

In the middle triangle, we can see that two of the sides are the same length and measure 8 cm while the third is 9 cm. When two of the sides of a triangle are the same it’s called an isosceles triangle. It’s a hard one to spell, but an easy one to recognize!

Scalene Triangle

In our last triangle, none of the sides have the same length, so this is called a scalene triangle.

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