Results 1 to 2 of 2

Math Help - Tricky Trig Task

  1. #1
    Newbie
    Joined
    Feb 2009
    Posts
    23

    Trionometry with a bit of pythag

    Hi i am new here.
    Can anyone point me in the right direction on this one please

    b=15.7

    I have gone as far as splitting the 2 triangles up and labeling the 2
    24.3² + DB = BC²
    15.7² + DB² = AB² (DB being the vertical unknown side)


    I then did AB + BC = 42 so thefore AB=42-BC and BC=42-AB

    I substituted these values in to the equation i came up with
    24.3² + DB = (42-AB)
    15.7² + DB² = (42-BC)

    I then tryed subtracting these away from each other as if a symlytaineous equation. (dont know if that was the right way to go about it)

    Thanks
    Last edited by jamm89; February 9th 2009 at 11:13 AM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,830
    Thanks
    123
    Quote Originally Posted by jamm89 View Post
    Hi i am new here.
    Can anyone point me in the right direction on this one please
    ...

    b=15.7

    ...
    I've modified your sketch a little bit. (see attachment)

    You've got two right triangles. Use Pythagorean theorem:

    \begin{array}{rcl}b^2+d^2& = &a^2 \\(40-b)^2+d^2&=&(42-a)^2\end{array}

    Expand the brackets and subtract the first equation from the second one:

    1600-80b = 1764-84a

    Now plug in the given value for b and solve for a. I've got a = 16.9. Thus d = 6.25.

    You now have all values to calculate the angles at B.

    I asume that you know how to add forces and that you need a parallelogram to get all partial forces.
    Attached Thumbnails Attached Thumbnails Tricky Trig Task-hang_truck.png  
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Tricky trig equation
    Posted in the Algebra Forum
    Replies: 2
    Last Post: November 30th 2011, 12:08 PM
  2. A tricky trig sub integral.
    Posted in the Calculus Forum
    Replies: 3
    Last Post: February 9th 2011, 05:30 PM
  3. tricky trig equations
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: September 14th 2009, 03:13 AM
  4. Trig. Identities; Tricky one :S
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: April 28th 2009, 05:58 PM
  5. two tricky trig problems
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: March 3rd 2008, 05:26 PM

Search Tags


/mathhelpforum @mathhelpforum