1. We will use the distance formula and the law of cosines to develop a formula to find the angle between two vectors.

5. Find the cosine of the angle and the angle between the following pairs of vectors. a is a position vector with terminal point (2, -1, 4) and b is a position vector with terminal point (4, 3, 5). a = 3i –j + 4k and b = -4i + 3j + k

6. Prove that u = -i + 3j – 2k and v = 2i + 2j + 2k are perpendicular.

7. Find the measure of <A in triangle BAH if B = (-2, 4, - 2), A = (3, 1, 1), and H = (5, 3, -1).

9. Section 15.2, Page 360, problems 1-19 odd, and 20-24.