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Fall 2014 – MATH 151, Sections 549-551 Quiz #1 DIRECTIONS. Read each problem carefully and work it out on a separate sheet of paper, if necessary. Put a box around the answer you believe best answers the question. Calculators are not allowed. Problem 1. If a circle has radius 10cm, what is the length of the arc subtended by a central angle of 72◦ ? (a) 720 cm (b) 4π cm (c) 40π cm (d) None of the above. Problem 2. Find a unit vector that has the same direction as h3, −5i. i (a) h √334 , √−5 34 (b) h 32 , 52 i (c) h1, − 53 i (d) None of the above. Problem 3. Express i and j in terms of a and b, where a = i − 2j and b = 3i + j. (a) i = 71 a − 27 b, j = 37 a − 17 b (b) i = 17 a + 27 b, j = − 37 a + 17 b (c) i = 14 a + 14 b, j = a + b (d) None of the above. Problem 4. If a = h2, 3i and b = h−3, 8i, find 2a − 16 b. (a) h 72 , 22 3 i (b) h 92 , 14 3 i (c) h 25 , 73 i (d) None of the above. 1