2. 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). sin 15 = A. sin 45 cos 30 - cos 45 sin 30 B. cos 45 cos 30 + sin 45 sin 30 C. cos 45 cos 30 - sin 45 sin 30 D. sin 45 cos 30 + cos 45 sin 30