Results 1 to 4 of 4

Math Help - Simple Statics / Trig problem

  1. #1
    Newbie
    Joined
    Apr 2009
    Posts
    4

    Simple Statics / Trig problem

    Okay I can't seem to think of how to solve this

    I basically need to have the y force be zero... currently I have

    90 + 70 sin(x) - 130 cos(x) = 0

    I feel like there is an inverse tan in my future but I can't get there...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Thanks
    1
    Hello msuMath311
    Quote Originally Posted by msuMath311 View Post
    Okay I can't seem to think of how to solve this

    I basically need to have the y force be zero... currently I have

    90 + 70 sin(x) - 130 cos(x) = 0

    I feel like there is an inverse tan in my future but I can't get there...
    This question doesn't make much sense. Do you need to solve this equation for x? If so, do this:

    130\cos x - 70\sin x = 90

    Let 130\cos x - 70 \sin x = R\cos(x + \alpha) = R\cos x\cos\alpha-R\sin x\sin\alpha

    \Rightarrow R^2 = 130^2 + 70^2 and \tan\alpha = \frac{70}{130}

    Can you complete it from here?

    Grandad
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Apr 2009
    Posts
    4

    Problem Edit

    I'm sorry I realized I mixed and matched problems from my whiteboard....

    I actually need to find the tensions on A and B, (I have the angles)

    so...

    A*cos(25) + B*cos(40) = -70*cos(10)
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Thanks
    1
    Hello msuMath311
    Quote Originally Posted by msuMath311 View Post
    I'm sorry I realized I mixed and matched problems from my whiteboard....

    I actually need to find the tensions on A and B, (I have the angles)

    so...

    A*cos(25) + B*cos(40) = -70*cos(10)
    Still doesn't make sense! You'll need a second equation in order to solve for A and B.

    Grandad
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. another simple statics problem
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: October 16th 2009, 11:55 PM
  2. Statics problem
    Posted in the Advanced Applied Math Forum
    Replies: 3
    Last Post: September 28th 2009, 08:49 PM
  3. one simple and one tricky statics question
    Posted in the Math Topics Forum
    Replies: 6
    Last Post: September 20th 2009, 05:44 PM
  4. Simple Trig Problem Which I Can't Seem To Get!
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: April 22nd 2009, 03:36 AM
  5. Statics problem
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: February 14th 2009, 04:43 AM

Search Tags


/mathhelpforum @mathhelpforum