1. Determine 2 positive and 2 negative principal angles for a terminal arm with a related acute angle of 20 in quadrant III. 2. Using the CAST rule, state the sign of each of the following: o sin 220 . COs 320 o tan 112 3. Determine sin 0 to 3 decimal places if cos 0 = 1/2 and 0 is an angle in quadrant IV. 4. The CAST Rule describes for a quadrant which ratios have positive values. Describe why the tangent ratio is positive only in quadrants I and III. 5. Given a point on the x-y plane, explain how you would determine a principal angle that would correspond to a terminal arm containing that point. 6. Show that the following is true: (sin 309)2 + (cos 309)2 = 1. 7. Determine precise values for the following: . sin (-30) . COS (-60) . tan (-450) 8. Determine precise values for the following: o sin (-210) . COS (300) . tan (-300) 9. Use special triangles to show that the following are true: o sin (2250) = sin (-459) . COs (30) = cos (-30) . tan (-60) = tan (1209) 10. For 120, show that tan T = sin T/cos T. 11. Express each of the following in a simpler form using one of the given identities: 0 1 - sinT . tan'T - sec-T 12. Prove the following identities: . cotT sinT = COST o sin T sec-T = sec-T - 1