## Tuesday, July 10, 2007

### Geometry Chapter 1.3 Segments and Their Measures

Geometry Chapter 1.3 Segments and Their Measures

I) Vocabulary & Postulates:

A) theorems: Rules that have been proven to be true.
Example: Triangle Sum Theorem: The sum of the measures of the interior angles of a triangle is 180 degrees.

B) Postulates or Axioms: Rules that we accept as true without proof.

C) Between - When 3 points are one a line, you may say that 1 point is between the others.

D) Segment Addition Postulate or Partition Postulate: If B is between point A and point C, then
AB + BC = AC

E) Distance formula: AB = √((x1 - x2)2 + (y1 - y2)2)

this is derived from the pythagorean theorem, where the difference of the x's is represented by "a" and the difference of the y's is represented by "b" and AB = c so

a2 + b2 = c2

F) Congruent Segments - Segments that have the same measure

Written:

Lengths are equal in length so: AB = CD

and

Segments are congruent so: line segment AB is congruent to line segment CD.