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Maths surface area Watch

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    The radius of a sphere is 3cm
    The radius of a base od a cone is 3cm
    The surface area of the sphere equals the total surface area of the cone
    Work out the slant height of the cone

    Please help!
    I got 3 but it is wrong!
    I did: 36pi=12pi+slant height
    Slant height= 36pi/12pi=3
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    (Original post by Lucofthewoods)
    The radius of a sphere is 3cm
    The radius of a base od a cone is 3cm
    The surface area of the sphere equals the total surface area of the cone
    Work out the slant height of the cone

    Please help!
    I got 3 but it is wrong!
    I did: 36pi=12pi+slant height
    Slant height= 36pi/12pi=3
    what did you get when finding the perpendicular height of the cone?
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    (Original post by TSRian123454321)
    what did you get when finding the perpendicular height of the cone?
    you dont need that
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    Surface area of sphere = 4 × πr²

    Total surface area of the cone = πrl + πr² (where l=slant height)

    Subbing in r=3 for the sphere and cone

    36π=3πl + 9π
    You cannot plus the π together
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    (Original post by Lucofthewoods)
    you dont need that
    oh, SA, not V

    oops
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    (Original post by Pentaquark)
    Surface area of sphere = 4 × πr²

    Total surface area of the cone = πrl + πr² (where l=slant height)

    Subbing in r=3 for the sphere and cone

    36π=3πl + 9π
    You cannot plus the π together
    what do i from there?
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    (Original post by Lucofthewoods)
    what do i from there?
    Move the 9pi to the other side You need to get the slant height so move everything to one side.
    From there you should know how to get l (slant height)
    What is the answer btw?
 
 
 
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