4.1 Radian and Degree Measure

Definitions

Trigonometry is the study of sides and angles of right triangles

Angles are two different rays with a common endpoint

The 2 rays in a angle are called the Sides

The common endpoint of an  angle is called the Vertex

Angle Measures are the measure of rotations or revolutions

Radians are the amount of rotation needed to make S=R

We count angles as clockwise or counterclockwise 

The side in which the angle lays on the x axis is the initial side

The side opposite of the initial side is the terminal side

Pi is the ratio of a circles circumference need to make S=R

Standerd Position

In standard position the vertex is centered on the origin

The initial side will always be on the positive x-axis

The angle implies both magnitude and direction meaning that it is a vector

It takes about 6.28 radi to get around circumference of a circle

The Arc is a portion of the circle

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Angle Relationships

Congruent means angles that have the same angle measure

Supplementary means the measures of the angle adds up to 180 degrees

Complementary means the measure of the angle adds up to 90 degrees

Co-terminal means the initial and terminal sides are at the same position

Proportion means two ratios of each other

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Formulas 
 this formula is only good if theta is in radians

To find a co-terminal angle one must go from the initial side until it reaches the terminal side. If one adds 360 to that angle it will also be co-terminal to that angle.