Results 1 to 5 of 5

Thread: Triangle in a cyrcle

  1. #1
    Newbie
    Joined
    Dec 2016
    From
    Austria
    Posts
    3

    Triangle in a cyrcle

    Does anyone know how to solve this? It has no information, just the answer is given, which is 72deg.
    Triangle in a cyrcle-screenshot_51.png
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Sep 2012
    From
    Australia
    Posts
    6,598
    Thanks
    1712

    Re: Triangle in a cyrcle

    Hey birkoof.

    You have an isosceles triangle, a hemi-circle and another circle [in the top].

    Try writing down as many variables as possible with your picture and show us the work you have done to write them as formulas so we can give you a hand.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Dec 2016
    From
    Austria
    Posts
    3

    Re: Triangle in a cyrcle

    Well, inside the triangle I have 2alpha + beta = 180deg.
    Using the Angle in the Center Theorem I get a X that is two times bigger than my beta (beta = x/2)
    Implementing that in 2alpha + beta = 180deg i came with the result that alpha is equal to 90deg - x/4.
    That's all i can get from the information given.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    Joined
    Jun 2013
    From
    Lebanon
    Posts
    820
    Thanks
    375

    Re: Triangle in a cyrcle

    triangle with angles $\displaystyle \beta ,\beta ,\alpha +\beta $ says $\displaystyle \alpha +3\beta =180{}^{\circ}$
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Dec 2016
    From
    Austria
    Posts
    3

    Re: Triangle in a cyrcle

    Quote Originally Posted by Idea View Post
    triangle with angles $\displaystyle \beta ,\beta ,\alpha +\beta $ says $\displaystyle \alpha +3\beta =180{}^{\circ}$
    Thanks, this helped a lot. Now i just express $\displaystyle \beta $ from the first triangle, which is $\displaystyle 180{}^{\circ} - 2 \alpha $ , put in the $\displaystyle \alpha +3\beta =180{}^{\circ}$ and i get that $\displaystyle \alpha = 360{}^{\circ} /5 $ which is $\displaystyle 72{}^{\circ} $ and the right answer. Thanks!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: Apr 23rd 2011, 08:10 AM
  2. Replies: 3
    Last Post: Apr 30th 2009, 07:41 AM
  3. Replies: 1
    Last Post: Oct 28th 2008, 07:02 PM
  4. Replies: 7
    Last Post: Jul 19th 2008, 06:53 AM
  5. Replies: 27
    Last Post: Apr 27th 2008, 10:36 AM

Search Tags


/mathhelpforum @mathhelpforum