Trigonometry and Precalculus, College of the Desert

Line Segments: is a straight line from point A to point B; denoted by AB(with a line above it).

Endpoints: Are the ponts in which the line hits and stops. (rather then a line that passes through the point).

Half Line or Ray: Is where you will have one endpoint and the the line segment passes through the pther point. (Donatred with AB with ---> above the AB).

Angle: An angle is formed by two rays with a common endpoint.

Vertex: A vertex is a common endpoint.

Initial Side: By keeping one ray of the angle fixed, it becomes the Initial Side.

Terminal Side: is the second ray that we allow to rotate to from an angle.

Degrees: One of the units of measure used for angles.

Acute Angle: An angle measuing less than 90^o.

Right Angle: An angle that measures exactly 90^o.

Obtuse Angle: An angle that measures between 90^o and 180^o (but NOT including).

Straigh Angle: An angle that measures exactly 180^o.

Perpendicular Lines: Lines that intersect at right (90^o) angles.

Complementary: are angles that when added will give a right (90^o) angle.

Supplementary: Angles that when added will give a straight angle (180^o).

Verticle Angles: Occure when two lines overlap resulting in 4 angles between the two lines, (as seen in the picture) the oppisite angles will always equal one another (<1+<2 = 180^o; <2+<4 = 180^o, therefore <1 must =<4 and by result <2 must =<3). These angles are what we call vertical Angles (the angles oppisit from one another).

Parallel Lines: Are lines that have the same slope but different intercepts, meaning that they will never touch.

• Transversal: A line that crosses any parralel lines is said to be trasnversal.
• Note: These will also than give us vertical Angles for each parrallel line that it crosses.

Corresponding Angles: Are angles that are the same value because they are the same position on one line while on a seperate but parallel line. (Please see picture above).

Alternate Interior Angles: Are angles in the oppisite position that has to be the same value do to Vertical angles and corresponding angles. (Please see picture above).