In Exercises 1-4, find the exact values of the sine, cosine, and tangent of the angle.
1. 11 π / 12 = 3 π / 4 + π / 6
2. 7 π / 12 = π / 3 + π / 4
3. 17 π / 12 = 9 π / 4 - 5 π / 6
4. - π / 12 = π / 6 - π / 4