Geometry Chapter 1

Distance

distance between two points A and B (written as AB) is the absolute value of the difference of the cordinates A and B

Congruent Segments

line segments that have the same length (if two lengths are equal segments are congruent)

Segment Addition Postulate

If B is between A and C then AB + BC = AC

Midpoint

point that divides the segment into two congruent segments

Segments Bisector

point, ray, line, line segment, or plane that intersects the segment at its midpoint

Midpoint Formula

(X1+X2)/2 , (Y1+Y2)/2

Distance Formula

√ (X2 - X1) ² + (Y2 - Y1) ²

Concave

If any part of a diagonal contains points in the exterior of the polygon

Convex

If no diagonal contains points in the exterior

Triangle

Perimeter= a + b + c, Area= bh/2

Square

Perimiter= 4 x sides, Area= sides²

Rectangle

Perimiter= L + W + L + W, Area= L x W

Angle

Angle can be named in 3 different ways: CAB, BAC, angle A

Congruent angles

Angles that have the same measure. The angles themselves are congruent, but their measures are equal

Angle Addition Postulate

IF you split the big angle any way you can then add them together

Angle Bisector

A ray that divides an angle into two congruent angles

Supplementary Angles

two angles that add up to 180 degrees

Adjacent Angles

An angle with the same vertex that shares a common side

Vertical Angles

Two nonadjacent angles formed by two intersecting lines

Linear Angles

A pair of adjacent angles whose non-common sides are opposite rays

Point

A dot with no dimension

Line

A straight path that never ends (one-dimensional)

Plane

A flat surface that extends forever

Collinear Points

Points that lie on the same line

Coplanar Points

Points that lie on the same plane

Line segment

Part of a line with two endpoints

Ray

Has one endpoint and continues forever

Opposite Rays

Two rays that share an endpoint and extend in opposite directions