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Math Help - Pre-Exam Review: Trig is killing me

  1. #1
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    Jun 2010
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    Angry Pre-Exam Review: Trig is killing me

    I hope you guys can help me! If I don't get a 75% on this exam I fail, and will not graduate.

    I'm having trouble clicking with Trig. I have the info recorded such as;

    Use Soh-Cah-Toa for right angled triangles
    Use Sine Law for ASS or ASA
    Use Cosine Law for SSS or SAS

    But when I look at a question I just freeze and don't know what to do.

    This one for example;

    A stencil is made out of plastic. What is the are of the plastic? The inner design is an equilateral triangle, inside a larger equilateral triangle, inside a square.

    I made a not-so-good drawing to try and help;
    Pre-Exam Review: Trig is killing me-2qth7vp.jpg

    If someone could please explain how to solve this I will be extremely happy ... until my next question.

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  2. #2
    MHF Contributor Unknown008's Avatar
    Joined
    May 2010
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    Mauritius
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    The area of a triangle can be obtained by:

    Area = \frac12 (base)(height)

    or

    Area = \frac12 (a)(b)sin(\hat{c})

    Try using the second formula, where c is the angle between the sides a and b.

    Post what you get.

    I prefer not doing the calculations, because I don't quite understand your question. I especially don't know what the square has to do with the area of the triangle...

    EDIT: Remember that in an equilateral triangle, all the angles within the triangle are 60 degrees, so c = 60
    Last edited by Unknown008; June 20th 2010 at 11:23 PM.
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