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Which angle are they asking for?

  1. Jun 3, 2006 #1
    im trying to figure out the angle of two these vector problems...ive found the magnitude but im unsure which angle i need to solve for

    question 1) A man lost in a maze makes 3 consecutive displacements so that at the end of his travel heis right back where he started. The first displacement is 2 m westward and the second is 23 m northward. Find the magnitude and direction of the third placement.

    i found the magnitude to be 23.1 with Ax= -2 and Ay= 23 Bx= 0 By= 23 Cx= 2 Cy=-23....the question asks for the direction (clockwise from due north?).....the angle i came up with was 85.03 (tan theta= 23/2) which is wrong


    question 2) A plane flies from base camp to lake A, a distance of 200 km at a direction of 20 degrees north of east. After dropping off supplies, the plane flies to lake B, which is 260 km and 30 degrees west of north from lake A. Find the distance and direction from lake B to the base camp.

    i found the magnitude to be 299 km with my sides being 57.9 (horizontal), 293.4, and the hypotonuse being 299.....and the question asks for the direction south of west

    i got 11.16 degrees (tan theta= 57.9/293.4)
     
  2. jcsd
  3. Jun 4, 2006 #2

    andrevdh

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    Homework Helper

    1) The tangent of the angle will be 2/23. The angle you got is its direction south of east. Depending on which convention you are suppose to use this is sometimes given as -84.07 degrees (anticlockwise wrt the x-axis is a positive angle) or the positive angle 360 - 84.07 degrees.

    2) You made the same mistake with the tangent here.
     
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