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Homework Help: Using Vectors to Find Displacement and Angle

  1. Feb 3, 2012 #1
    1. The problem statement, all variables and given/known data
    A person walks in the following pattern: 4.1 km north, then 2.0 km west, and finally 2.5 km south.

    2. Relevant equations
    (a) How far (in km) and (b) at what angle (measured counterclockwise from east) would a bird fly in a straight line from the same starting point to the same final point?

    3. The attempt at a solution
    I know that I need to create the triangles for 4.1, 2.0, and 2.5, and use basic trigonometry (sine and cosine) to find the values of each of their x and y components, but I am not sure which reference angles to use 30 degrees, 60 degrees, 45 degrees? How am I supposed to tell? I know where to go from there, you add up all of the x components, and then all of the y components, and then create your final triangle and determine the displacement value using the Pythagorean Theorem. Then you determine the angle by using the inverse of tangent.
    I just need help with determining the angles for those three triangles.
  2. jcsd
  3. Feb 3, 2012 #2


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    Homework Helper

    Hi sb13,

    Make a drawing. Everything will be simple.

  4. Feb 3, 2012 #3
    Thank you. I figured it out.
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