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Thread: Finding an angle within this triangle

  1. #1
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    Finding an angle within this triangle

    Hi,

    All variables given in blue are known values. I am trying to calculate the angle X in terms of the variables I know. How can I do this?

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  2. #2
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    Re: Finding an angle within this triangle

    Hello, Corpsecreate!

    All variables given in blue are known values.
    I am trying to calculate the angle X in terms of the variables I know.


    The sum of the (interior) angles of a triangle is always equal to 180o.

    Hence: .$\displaystyle A + B + (C + X) \;=\;180$

    Got it?
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  3. #3
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    Re: Finding an angle within this triangle

    You can calculate the angle between the side$\displaystyle b$ and the horizontal, add $\displaystyle X$ to that and you have the angle $\displaystyle C.$
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  4. #4
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    Re: Finding an angle within this triangle

    Quote Originally Posted by Soroban View Post
    Hello, Corpsecreate!


    The sum of the (interior) angles of a triangle is always equal to 180o.

    Hence: .$\displaystyle A + B + (C + X) \;=\;180$

    Got it?
    Angle $\displaystyle C$ is the entire interior angle, not just the angle up to the horizontal. $\displaystyle A + B + C$ will give $\displaystyle 180$, $\displaystyle A + B + (C + X)$ will give a number larger than $\displaystyle 180$.

    Quote Originally Posted by BobP View Post
    You can calculate the angle between the side$\displaystyle b$ and the horizontal, add $\displaystyle X$ to that and you have the angle $\displaystyle C.$
    The angle side $\displaystyle b$ makes with the horizontal is $\displaystyle A + phi$, I dont see how adding $\displaystyle X$ to this angle would give me angle $\displaystyle C$?

    NVM: Question has been solved!
    Last edited by Corpsecreate; Oct 21st 2012 at 10:26 PM. Reason: Problem has been solved.
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  5. #5
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    Re: Finding an angle within this triangle

    The angle side $\displaystyle b $ makes with the horizontal is $\displaystyle A + phi$, I dont see how adding $\displaystyle X$ to this angle would give me angle $\displaystyle C$?
    NVM: Question has been solved!
    The angle referred to is the complement of the one you state, that is, $\displaystyle 180 - (A+\phi).$

    This will equal the angle below the horizontal at $\displaystyle C.$ Add $\displaystyle X$ and you get $\displaystyle C.$

    BTW., some labels on the diagram would have helped.
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