16. To answer questions 12-17, use the formulas for functions of the difference and sum of two angles to find, without tables or calculator, the cosine, sine, and tangent of the angle: 15 (using 45 and 30). tan 15 = O A. 1+tan 45 tan 30 tan 45-tan30 tan 45-tan30 B. 1+ tan 45 tan 30 C. tan 45+tan30 1-tan 45 tan 30 OD. 1-tan 45 tan 30 tan 45+tan30