Points, Lines, Planes and Angles

point, line, plane
A line is a set of points.
Two points determine a line.
An end point is a point where a line begins.
A Ray starts at an end point going to infinity
A half line is a ray without the end point
a line segment is a line between two end points
Two lines in the same plane that do not intersect are parallel.
Any non-co linear points determine a plane
A plane divided in half produces two half-planes
Angles
Two rays with a common end point determine an angle.
The common end point is a vertex
The rays are the sides
We measure angles in degrees
An angle that measures 90 degrees is a right angle
An angle that measures less than 90 degrees is an acute angle
An angle that measures more than 90 degrees is an obtuse angle
An angle that measures 180 degrees is a straight angle.
Two angles with a common vertex, common side, but no common interior points are adjacent angles.
if two adjacent angles sum to 90 degrees, they are complementary angles
If two adjacent angles sum to 180 degrees they are supplementary angles.
When two intersect the non adjacent angles are vertical angles.
Vertical angles have the same measure
A and B , C and D are vertical angles
when two lines are crossed by a another line at two different points, the line is called a transversal
3 4 5 6 are interior angles
1 2 7 8 are exterior angles
If the lines are parallel, alternate interior and alternate exterior angles are equal.

Do 45 - 90 odds, page 483.