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.
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