1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: Solving for Coordinate Angles in Statics Question

  1. Sep 9, 2012 #1
    Edit: Nevermind, it has been resolved.

    1. The problem statement, all variables and given/known data
    I have been attempting to solve what seems like a relatively pedestrian statics questions, but for some reason my answer is being marked as incorrect. The problem is as follows:

    Determine the magnitude and coordinate direction angles of the resultant force acting at A. Given that F_B = 640N and F_C = 450N.


    2. Relevant equations

    N/A (no specific equations needed)

    3. The attempt at a solution

    I solved for the value of the resultant vector without any trouble by assigning point A as the origin and adding the components of the two original vectors. This gave me a value of 998.05=R. The resultant vector had the equation of 626.667i+13.33j+776.667k.

    My attempt at solving for the coordinate angles ended in failure:

    For example:
    alpha=cos^-1(626.667/998.05)=51.1 degrees, which is incorrect.

    Any thoughts would be greatly appreciated.
    Last edited: Sep 9, 2012
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted