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Thread: Geometry Question - Please

  1. #1
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    Geometry Question - Please



    Hi, so i came very close to the "correct answer", i just can't understand why they took certain things into considerations. Ill try to translate the task as best as i can.

    You're going to make the foundation and the floor of concrete , the dark blue area is the ground foundation and is 25 cm ( 0.25m ) broad.

    A) What is the area of the light blue and dark blue for this figure?


    B) In the lightblue area you're going to make a 10CM ( 0,1m) thick concrete layer. The ground foundation shall be 40cm in height (0.4m)
    How many cubic meters (m^3 ) of concrete do you need?
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  2. #2
    MHF Contributor

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    Re: Geometry Question - Please

    Why have you not shown any attempt to do this your self? It is not very difficult to see that we divide the entire area into two rectangles- a small, 1 m by 4 m, rectangle at the top and a large 14 m by 7 m rectangle at the bottom. What is the area of each of those? What is the total area?

    To find the area of just the light blue area, reduce the sizes by removing the "0.25 m" stripe. In the small rectangle, we deduct 0.25 m from each side, so the length is 4- 0.25- 0.25= 3.5 m, and deduct 0.25 m only from the top so the width is 1- 0.25= 0.75m. What is the area of that? For the large rectangle, we are deducting 0.25 m from both sides and from top and bottom (ignore the fact that the dark blue does not go all the way across the top for the moment). The large light blue rectangle has length 14- 0.25- 0.25= 13.5 m and width 7- 0.25- 0.25= 6.5 m. What is the area of that? Now add back on the light blue area in the top middle where the dark blue stripe is missing: it has length 3.5 m and width 0.25 m. Add its area to the previous figure.

    To find the area of the dark blue region, subtract the area of the light blue from the total area. To find the volume of concrete needed multiply the area of the light blue region by 0.10 m and the area of the dark blue region by 0.40 m and add.
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