1. Trigonometry Section 7.1 Find measures of angles and coterminal angle in degrees and radians Trigonometry means “triangle measurement”. There are two types of trigonometry: a. Triangle trigonometry b. Coordinate trigonometry. A basic concept of trigonometry is the angle. An angle is formed by rotating a ray. A counterclockwise rotation creates a positive angle. A clockwise rotation creates a negative angle.

2. Angles can be measured using three different units. a. revolutions b. degrees c. radians One revolution equals 360 degrees. One degree equals 60 minutes. One minute equals 60 seconds. DMS notation for an angle: 24 o 12’ 45” Decimal Degree notation (DD) for an angle: 56.875 o

3. Convert to decimal degrees. (DD) 41 o 45’ 30 “

4. Convert to DMS notation. 35.125 o

5. A central angle of a circle has a measure of one radian when its intercepted arc has the same length as the radius of the circle. Formula to find the measure of a central angle in radians Θ = s/r Θ is one radian when r = s.

6. Find the measure of the angle Θ in radians.

7. One revolution = 360 o = 2π radians One radian ≈ 57.2958 degrees One degree ≈.0174533 radians Convert ⅗π to degrees Conversion Formulas Radians to degrees: multiply by 180/π Degrees to radians multiply by π/180 Convert 125 o to radians

8. Common conversions

9. An angle in standard position has a vertex at the origin and its initial ray on the positive x axis. Two angles that have the same initial and terminal rays are coterminal angles.

10. Find a positive and a negative coterminal angle for each of the following. 30 o 460 o ¼π¼π 4.5 radians

11. assignment Page 261 Problems 2-14 even, 18,20,26,28,30,32