Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Trigonometry with Vectors

  1. Oct 30, 2011 #1
    [PLAIN]http://img832.imageshack.us/img832/449/physicsu.png [Broken]
    By c42711 at 2011-10-30

    I am supposed to find the X and Y components of the above vector. What I tried to do first was dot in a line, forming a triangle. I then tried to find the length of that line using tangent. I got 431.8, but I am not sure that is right. Next, I used the Pythagorean theorem to try to find the X and Y components, I got some crazy numbers, so I know I'm doing something wrong. Any help would be fantastic. Please & thank you.:)
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Oct 30, 2011 #2
    Tangent is not the correct function to use. 147km is the hypotenuse of the triangle.
     
  4. Oct 30, 2011 #3
    You'd need to use sine for the vertical and cosine for the horizontal. The sine of the angle is y / the hypotenuse, so y = sin71.2 * h. Similarly, x = cos71.2 * h. Hope that helps.
     
  5. Oct 30, 2011 #4
    So I tried that and got:
    Fx= 47.4 km
    Fy= 139 km

    Does that seem correct?
     
  6. Oct 30, 2011 #5
    Yeah, those are the correct values.
     
  7. Oct 30, 2011 #6
    Than you so much, you're the best.:)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook