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Thread: Grade 9 Math Help LOL

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    Bettser's Avatar
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    Grade 9 Math Help LOL

    Okay, so my sister called me right now and shes freaking out because she cant get a question on her assignment and it's getting late and she has a midterm tomorrow.


    Its for #4. A is 1500 cm^2 or or 15m. Now... what the hell is b? The book is saying the answer is 1.

    Im getting 45 cans for painting the one side, or 90 for the back and front.

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    If your answer in A is correct, 1500cm^2, then 6 signs will take 9000cm^2.

    1m^2 is 100cm x 100cm =10000cm^2, so 1 can of paint is the correct answer.

    Edit: @Bettser

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    Quote Originally Posted by goodieboy View Post
    If your answer in A is correct, 1500cm^2, then 6 signs will take 9000cm^2.

    1m^2 is 100cm x 100cm =10000cm^2, so 1 can of paint is the correct answer.

    Edit: @Bettser
    Still doesnt make sense to me.

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    One side=1500cm^2
    Six signs (one side)=9000cm^2

    One paint can=200x200cm=40000cm^2

    So one can would be needed, whether they painted one side on each or both.
    Last edited by Ghosts; 12-03-2013 at 11:08 PM.

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    Quote Originally Posted by Bettser View Post
    Still doesnt make sense to me.
    Google 1 m^2 = how many cm^2 and you'll know why it's 1 can. Yea @Ghosts you're right.

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    Okay so I feel like you aren't getting how everyone is doing this and you want that as well not just the answer so here it goes.

    To find the area of a right triangle you need to do [a*b]/2 (a and b are the lines coming off the right angle. The other line "the hypotenuse would be c" since you aren't given A and B you have to do a bit of fun math. Aka the Pythagorean thing. Which you can you to find the length of a side of any right triangle given you have two others... which we do! So a^2 + b^2 = c^ let's say in this case

    [I'm really tired and my brain is having a moment so I cannot actually tell if the 10cm is referring to the whole line or just the part coming off. If it's only part of it the whole side would actually be 20cm. So I'm going to use 20 okay.]

    So we know that C= 25 and B= 20 and now plug that in to get A. [a^2 + 20^2 = 25^2 -> a^2 +400 = 625 -> a^2 = 225 -> get the square root and A= 15

    Now for area [15*20]/2 = 150

    There are two of these triangles so you can double that for the whole sign. Meaning the area of the tip is 300cm.

    The rectangle part of the sign is simple 60*20 = 1200 cm.

    Now put the whole thing together! 1200 + 300 = 1500cm. With that you have to paint 6 signs so multiply by 6.

    1500*6 = 9000cm!

    Now like @goodieboy about the area of the paint being 1m^2 = 10000cm^2

    So yes. 1 can of paint. Hope this is clear on the how and why and such!

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    Thanks guys.

    I understand now but like I dont know. I wouldn't have thought that out of the box in grade 9 xD

    The way I explained it to her was like;

    One can = 2m^2 = (200cm)^2 = 40000cm^2 so yea, one can.

    Thanks a ton!

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