Words of “Wiz-dom”–There are three basic rules about triangles that you need to remember. First, don’t forget the “Wizard’s Theorem” which applies to all triangles not just right triangles. The sum of the lengths of any two sides (even the short sides) of a triangle is greater than the length of the third side and the length of the third side is greater than the difference of the other two sides. This pair of rules can be written as the following:
SUM > 3rd side > DIFFERENCE
Second, the length of the sides of a triangle are in proportion to the angles that define (are opposite) them. That is, the longest (largest) side is opposite the largest angle and the shortest (smallest) side is opposite the smallest angle.
Third, the most common rule about triangles that you need to remember is the angles of a triangle add up to 180o.
Let’s do two quick refresher exercises for exterior angles (a).
Words of “Wiz-dom”-Remember middle school? About then you were taught that the area of a triangle is 1/2 the length of the base times the height of the triangle. It is expressed by the following formula: