Reference angle is the smallest angle that the terminal side of a given angle makes with the x-axis. It is positive and always lies between 0 and 90 degrees (Acute angle). Reference angle can be in any of the four quadrants. When determining the reference angle, vertically drop (raise) the line to the horizontal axis (x-axis). Angles in first quadrant are their own reference angles. The angle is measured by the amount of rotation from the initial side to the terminal side.
|What are Angles||Angle of Depression and Angle of Elevation||A Acute Angle||A Obtuse Angle|
|A Right Angle||A Straight Angle||Adjacent Angle||All Types of Angles|
|Angle in Pentagon||Angle Relationship||Angle Supplementary||Angles Complementary|