TRIANGLES

The basic facts are that triangles are three points on a plane with each point connected by a line to the two other points.  The lines make angles with each other.  One interesting fact, true of all triangles, is that the angles always add up to 180 degrees.  This fact is used in many mathematical theorems.  Here is a web site offering many definitions of words pertaining to triangles.  Take notes if you like.  Visit Wolfram's MathWord.

How about some speacial triangles and facts.  One special triangle is the Equilateral Triangle.  If we know that the angles of all triangles add up to 180 degrees and that all triangles have 3 angles and that the angles of an equilateral triangle are equal, what do we know about their size?  Right !  180/3 = 60 so the angles of all equilateral triangles are 60 degrees.

The greeks as noted earlier were very active in the study of geometry.  One very famous greek discovered and proved a fundamental fact about all right triangles.  A right triangle, as you know, is a triangle having one right (90 degree) angle.  Why could a triangle not have more than one 90 degree angle?  The very famous greek was a man named Pythagoras and the fact that he discovered is called the Pythagorean Theorem.  Visit the web page and read about the theorem.  See if you can prove it.  In your career, you will encounter this theorem again and again.

Right triangles are a very special case of triangles in general.  They are the basis for calculating the trigonometric ratios sin, cos, tangent and the others.  Of all right triangles, there are a few 'special' ones.  Let's think about Special Right Triangles.

Well this is the end of this weblesn.  We hope you enjoyed it and will continue your study of geometry.

LET NO MAN WHO IS IGNORANT OF GEOMETRY ENTER THESE DOORS

Inscription above the door of an ancient Greek school run by Plato