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Math Help - Areas and Perimeters.

  1. #1
    Newbie suckatmaths's Avatar
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    Areas and Perimeters.

    I have this assignment at school to do with Areas and Perimeters. This is the final question, and I am totally stuck.

    b) Find x if the total area is to be 1000m2

    c) find the cost of the outer border given that materials cost $12.75 per metre.

    Diagram:

    ImageShack - Image Hosting :: picture541.jpg

    Is anyone able to help me?

    Oh yes, if it helps, this is the expression:

    A = x2 (1 + PI/2) m2
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  2. #2
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    earboth's Avatar
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    Quote Originally Posted by suckatmaths View Post
    I have this assignment at school to do with Areas and Perimeters. This is the final question, and I am totally stuck.

    b) Find x if the total area is to be 1000m2

    c) find the cost of the outer border given that materials cost $12.75 per metre.

    Diagram:

    ImageShack - Image Hosting :: picture541.jpg

    Is anyone able to help me?

    Oh yes, if it helps, this is the expression:

    A = x2 (1 + PI/2) m2
    1. The complete area consists of a square with side length x and two complete circles with radius r = \frac x2. Therefore solve for x:

    1000 = x^2 + 2\cdot \pi\cdot \left(\dfrac x2\right)^2

    2. The perimeter of the area is the circumference of two circles with radius r = \frac x2. Therefore the costs of the border are

    c = \$12.75 \cdot 2 \cdot 2\pi\cdot  \frac x2

    Use the value of x from #1 to solve #2.
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