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Building Up Geometry
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Triangles

A triangle is a polygon with three (3) sides, three vertices, and three angles, which are straight line segments. There are six different triangles, and here are 3. They are the equilateral, isosceles, and scalene triangles. An equilateral triangle has equal sides and equal angles.

An isosceles triangle has two long sides and one short side.

A scalene triangle has no congruent sides and angles.                               Equilateral              Isosceles                    Scalene

Right, Obtuse, and Acute  triangles have angles that are right, obtuse, and acute angles. When you know right, obtuse, and acute angles, you can spot the triangles easily.

A right triangle has one right angle that measures 90 degrees.

The next triangle is an obtuse triangle and it has an obtuse angle which measures more than 90 degrees, but less than 180 degrees.

The last triangle is an acute triangle and it has an angle that is smaller than 90 degrees.

Right Triangle           Obtuse Triangle             Acute Triangle

All  triangles  have a total of 180 degrees. You can find triangles all over the place. For example, there may be a triangle on one side of your house. Triangles are featured a lot in architecture because they are one of the most stable and strongest structures. One other example of a structure that has stood the test of time  is the Menkaure Pyramid in Gaza, Egypt.
All triangles have legs. One example is a right angle. A right angle's legs are the two perpendicular lines.

A hypotenuse is the side of the right angle opposite of the right side.
A Pythagorean Theorem means that in a right angle, the area of the square on the hypotenuse is equal to the sum of the areas of both sides.

Pythagorean Theorem

Written as: a2=b2+c2

Pythagoras was a famous Greek mathematician born about 569 B.C.

This is a picture of the Pythagorean Theorem
and  the Greek mathematician Pythagoras.