Find the angle between u and v in radians. 19) u = 3i + 9j + 6k, v = 6i + 6j + 7k A) 1.48 B) 0.39 C) 1.09 D) 1.18 20) u = -91 + 2j - 8k, v = 5i + 9j - 9k A) 1.57 B) 1.30 C) 0.27 D) 1.44 21) u = 8i - 4j - 9k, v = 8i + 4j - 2k A) 0.60 B) 1.57 C) 0.97 D) 1.30 22) u = -2i - 6j, v = 7i + 6j + 8k A) 2.28 B) 1.84 C) -0.70 D) 1.58 23) u = 3j - 7k, v = 7i - 5j - 10k A) 0.99 B) 1.33 C) 0.58 D) 1.57 24) u = 9i, v = 9i - 8j A) 0.73 B) 1.20 C) 1.56 D) 0.84 Find a function r(t) that describes the line or line segment. 25) The line through P(4, 9, 3) and Q(1, 6, 7) A) r(t) = (4 - 3t, 9 + 4t, 3 - 3t) B) r(t) = (4 - 3t, 9 - 3t, 3 + 4t) C) r(t) = (4 - 3t, 9 - 4t, 3 + 3t) D) r(t) = (4 + 4t, 9 - 3t, 3 - 3t) N 26) The line segment from P(2, 7, 3) to Q(3, 1, 1) A) r(t) = (2 - t, 7 + 6t, 3 + 21); 1 st s2 B) r(t) = (2 + t, 7 - 6t, 3 - 21); 1 sts2 C) r(t) = (2 + t, 7 - 6t, 3 - 21); 0sts 1 D) r(t) = (2 - t, 7 + 6t, 3 + 21); 0sts1 Evaluate the limit. 27) lim = (2 cost i + 5 sin t j) t-37/2 A) 5j B) 21 - 5j C) 2i D) -5j 28) lim = (2e-ti + 8e-tj) t-+n 2 A) -i - 4j B) i + 4j C) 4j D) - 4j