TRIANGLE CONSTRUCTION



http://www.mathopenref.com/consttrianglesss.html

1)Draw all sides (or angles) with your ruler.
2)Start with one side, it doen´t matter which: draw the first side.
3)Take the second side with your compass (no matter which) and draw an arc from the end of the first side.
4)Take the third side with your compass and draw, from the another end of the first side.
5)Close the triangle: join the third point (given by both arcs). Draw the other two sides.

6)REMEMBER that there can be more than one solution for each exercise!


EXERCISES:

1)a=3cm, b=3cm, c=3cm.

2)a=4cm, b=5cm, c=6cm.

3)a=2.5cm, b=c=5cm.

4)a=5cm, b=4.5cm, c=4cm.

TRIANGLE TYPES

According to their angles and sides, triangles can be classified as:

With this theory will be enough. Do you find it interesting? 

Check this shape and count HOW MANY TRIANGLES are therein?

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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?