Points, Lines and Angles

• A point is a dimensionless position in space.
• Labeled, normally as a dot, and an upper case letter. (A)
• A line is a set of points.
• Labeled by two points, with a two direction arrow above.
• A Half Line starts at, but does not include one end point.
• A Ray starts at and includes an end point.
• A Line Segment Is a line between and including two end points.
• An angle is formed when two rays intersect.
• Angles are measured in degrees, radians and other units.
• A right angle has a measure of 90 degrees.
• An acute angle has a measure of less than 90 degrees.
• An obtuse angle has a measure of more than 90 degrees but less than 180 degrees
• A straight angle has a measure of 180 degrees.
• Two angles are complementary if the sum of their measures is 90 degrees
• Two angles are supplementary if the sum of their measures is 180 degrees
• Do problems Page 425 45 through 64.
• When two lines intersect, vertical angles are formed.
• Vertical angles have the same measure.
• Parallel Lines Cut by a transversal.
  • alternate interior angles are equal.
  • alternate exterior angles are equal
  • horizontal angles are equal.