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Need help with physics homework!

  1. May 27, 2012 #1
    Hi, have a physics test coming up on Tuesday, and I was wondering if you all would like to help me out with a couple questions!

    1)
    A highway is to be built between two towns, one of which lies 70.0 km south and 72.0 km west of the other. (a) What is the shortest length of highway that can be built between the two towns, and (b) at what angle would this highway be directed, as a positive angle with respect to due west?

    I need part b of this, the answer for a was 100

    2) The drawing shows a person looking at a building on top of which an antenna is mounted. The horizontal distance between the person’s eyes and the building is 81.8 m. In part a the person is looking at the base of the antenna, and his line of sight makes an angle of 36.0o with the horizontal. In part b the person is looking at the top of the antenna, and his line of sight makes an angle of 39.3o with the horizontal. How tall is the antenna?

    For this problem, i tried using 81.8tan(39.3) - 81.8tan(36) but kept getting a weird number.

    Thanks for the help!
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 27, 2012 #2
    Maybe you can show us that weird number.
     
  4. May 28, 2012 #3
    I got -3351.513245
     
  5. May 28, 2012 #4
    Wait!! My calculator was in radians. My mistake~
    so i only need help with is part b for the first one!
     
  6. May 28, 2012 #5
    For part (b), draw out a vector diagram, and relate the angle to the two sides of the triangle(use trigonometry)
     
  7. May 28, 2012 #6
    Draw a picture and use trigonometry.
     
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