1. Wednesday, Jan 9, 2013

2. Objective 1 Find the reference angle for a given angle A reference angle for an angle is the positive acute angle made by the terminal side of the angle and the x- axis. Find the reference angle for 218 0. How far from x-axis is terminal side of angle? 218 – 180 = 38 38 0

3. b) 1387 0 1387 – 360 (3) = 307 This side is either 0 0 or 360 0. Use 360 0. 360 – 307 = 53 Reference angle = 53

4. Find exact value for cos(-240 0 ) Begin by finding the 1 st positive co-terminal angle. 360 – 240 = 120 Next find reference angle 120 is in quadrant II. 180 – 120 = 60. Use table to find trig values for 60 0. Remember cos is negative in quadrant II cos(-240) = -1/2

5. Evaluate cos 120 + 2 sin 2 60 – tan 2 30 Cos 120 = cos 60 (reference angle) = -1/2 Sin 60 = √3 / 2 Tan 30 = √3 / 3 Plug in -1/2 + 2(√3 / 2) 2 – (√3 / 3) 2 = -1/2 + 2(3/4) – (1/3) = 2/3

6. Find all values of θ, if θ is in the interval (0 o,360 o ) and cos θ = -√2/2 If cos is negative, the angle must be in quadrant II or III. Using chart of known values, the angle is a 45 o angle. The angle could be 180-45 = 135 or 180 + 45 = 225

7. Assignment P 713 – 715 Mult of 3 and all of 10-17.