March 30, 2017

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You now have 6 different posts going for the same "cake question"
I am not going to keep going back to see which one you replied to. Stay with one posting please.

I just notice one way down the list where you did part a) Calculate the area on top of the slice that has been cut out and you got 50.3 something

area = (60/360)(144π) = 24π = 75.4

  • FOR NABIAH - ,

    ok sorry, but i don't get how you are getting that? where is the 60 and 144 coming from, my answers for both a and b were right- its just c

  • FOR NABIAH - ,

    have you looked at my long explanation to see how I attempted it?

  • FOR NABIAH - ,


    You said after a slice is cut, there are 320° of cake left, so the slice must have had a sector angle of 60° , since there are 360° in one rotation.

    Area of the whole top is πr^2 = π(12^2) = 144π

    If you were trying to do it by ratios, then

    area/144π = 60/360
    area/144π = 1/6
    area = (1/6)144π = 24π like I had

    b) the volume of the whole cake = (πr^2)h
    so again, a slice is 1/6 of that volume.

  • FOR NABIAH - ,

    Nabiha, I just realized I made a very silly error.
    Of course then angle of the slice is 40° and not 60

    I am sorry to have caused you all this trouble.

    so your answer to a) would be
    (40/360)(144π) = 50.3, which I believe you had

    change all my other calculations using the 1/6 to 1/9
    because 40/360 = 1/9

  • FOR NABIAH - ,

    ok, but what about question c) what formulas would I use, is my method correct?

  • FOR NABIAH - ,

    that is by using sections and work out the area of the 3 parts: 1)rectangle * 2(shown by the slice being cut), 2)long rectangle around cake (stops when you get to slice) and finally 3)the top and bottom of the cake ( angle is 320)

    how do I work out the area of 2) and 3) so then I can add them to get the total surface area with the slice cut
    Ive already shown this in my long explanation of my method to c) can you please comment on that one aswell.

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