TRIANGLES-Definition

A triangle, as you might know, is a geometrical shape (polygon) with three sides. 

Every triangle has three SIDES and three ANGLES.

Those three angles ALWAYS ADD to 180º : (α + β + γ = 180º)

What´s the name of the three sides of this triangle?

___   ___   ___

AB, BC, CA

All sides are segments, but are also called after one small letter,

which is the same than the opposite vertex.

We use then : 

                    ____

c instead of AB,

                     ____

a instead of BC

                ____

and b instead CA .

You have to know also that ANGLES are named after greek letters:

A=α  Β=β  C=γ     (α + β + γ = 180º)

You must know them. That way names and formulas become easier for you, dear students.

Now, some questions for you to discover:

DO YOU KNOW how many triangles do exist?

CAN YOU find examples for triangles IN NATURE? 

...and in HUMAN WORLD? 

IS THERE any triangle with more/less than 180º angles?