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  1. #1
    Para DICE's Avatar
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    Maths - trigonometry AREA of triangle

    I understand the concept of finding the area:

    1/2 x Base x Height Sin(Angle) = Ans

    But i don't understand how you reverse the operation to find the Length, such as the image here:


    [Q] The area of the triangle ABC is 33.5cm^2.

    Calculate the length of BC.



    --

    Please give me the Rule, and how you did it.

  2. #2
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    first of all, you're combining your equations. the area of a triangle in this case is not .5 base x height sin(ang), it's .5 (side a) (side b) sin (ang). to find the side, just plug your values in and you should have only 1 unknown.

    I got 10.0087

    Work:

    area=.5(sidea)(sideb)sin(angle)

    sin(73) * 0.5 * 7 * b= 33.5

    33.5/sin(73) * 0.5 * 7 =b

    b= 10.0087

    I think i'm right, check me and let me know if my math is wrong.
    Last edited by SammyZee56; 01-31-2011 at 11:11 PM.

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    Para DICE (02-01-2011)

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    Alen's Avatar
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    You might wanna refresh some of that basic algebra from primary school

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    Para DICE (02-01-2011)

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    Para DICE's Avatar
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    Quote Originally Posted by Coeus View Post












    You might wanna refresh some of that basic algebra from primary school
    Primary school? really... damn in the US you learn things early..primary school i was learning my time tables.

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    Quote Originally Posted by Para DICE View Post
    Primary school? really... damn in the US you learn things early..primary school i was learning my time tables.
    Not the US >_>

    And basic algebra (aka a*b=c => a=c/b) is most definitely primary school stuff.

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    Para DICE's Avatar
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    Quote Originally Posted by Coeus View Post
    Not the US >_>

    And basic algebra (aka a*b=c => a=c/b) is most definitely primary school stuff.
    Isn't that reverse operation?

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    Quote Originally Posted by Para DICE View Post
    Isn't that reverse operation?
    Err ... basic algebra? Take a look online, it'll help you probs: Interactive Mathematics - Learn math while you play with it!

  10. #8
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    wait, me? i dont think so. i did put a slash there, just no parentheses. the slash is generally an accepted symbol for division. if i did make a mistake, please be specific so i dont do it in the future. thanks.