4)+Given+an+angle+measure,+find+reference+angles+and+coterminal+angles.

= **Reference and Coterminal Angles:** =

W//HY?// I chose this topic because I always got these two terms mixed up. I always could not quite make out which one was which. I also felt that it would be useful for me to study these a little bit more considering I work with angles at work all of the time. The more I can learn about angles, the better.

//COTERMINAL ANGLES:// These are two or more angles in standard position with the same terminal side. Standard position is where the vertex is at the origin and the initial side along the positive X-axis. These angles are found by taking the measure of the angle, and adding multiples of 360 degrees. Every angle has infinite coterminal angles. Example: Source:http://hotmath.com/hotmath_help/topics/coterminal-angles.html

//REFERENCE ANGLES:// This is the acute angle formed by the terminal side of the given angle and the X-axis. This is only if the angle is not one of the four quadrantal angles (90, 180, 270, 360). If the angle is greater than 360, or less than 0, the reference angle can be found by using a coterminal angle. Source: [] Formulas for Reference Angles: Quadrant 1= Actual Quadrant 2= 180-angle Quadrant 3= Angle-180 Quadrant 4= 360-angle
 * Example:** [[image:http://img.sparknotes.com/figures/0/0954c20cdd40ed30b40d3e5107516db0/reference.gif]]

//EXAMPLE PROBLEMS://

Q: If the angle measure is 50 degrees in standard position, find one coterminal angle. A: 50+360= 410 degrees

Q: If the angle measure is 110 degrees in standard position, find the reference angle. A: 180-110= 70 degrees

Q: If the angle measure is -120 degrees, find the reference and one coterminal angle. A: -120+360= 240 degrees (coterminal) 240-180= 60 degrees (reference)

Q: If the angle measure is 279 degrees, find the reference and two coterminal angles. A: 360-279= 81 degrees (reference) 279+360= 639 degrees (coterminal) 279+(360(2))= 999 degrees (coterminal)

**//FINAL PROBLEM://**

**If the angle measure is 336.7 degrees, find the reference and two coterminal angles!**

// **Video / Powerpoint** // video -Henry Burke, Period 1