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-   -   Solid mensuration. Finding the value of h (https://www.askmehelpdesk.com/showthread.php?t=327343)

  • Mar 10, 2009, 07:42 AM
    ylzik
    solid mensuration. Finding the value of h
    is what I've been doing correct so far:

    find the value of h for a spherical segment whose volume is equivalent to 159pi if the radii of the bases are 5m and 4m respectively

    v= (pi/6)(3a^2 + 3b^2 + h^2) h

    v= 0.52 ((3)(5^2) + (3)(4^2) + h^2) h

    = 0.52 ((3)(25) + (3)(16) + h^2) h

    = 0.52 (75 + 48 + h^2) h

    =(39 + 24.96 + 0.52h^2) h

    =(63.96 + 0.52h^2) h

    if yeah, how do I find the value of h?

    if not, where did I go wrong?

    thank youuuuu so much for any help!!
  • Mar 10, 2009, 08:21 AM
    Perito

    I answered you in the next thread, but I don't have time to follow your work, so I haven't checked it.

    https://www.askmehelpdesk.com/math-s...-h-327327.html

    Since you know the value of v (159 pi), you can solve it using the calculator whose URL I posted.
  • Mar 10, 2009, 08:37 AM
    ebaines

    Please help me understand the spherical segment that you are analyzing - specifically, how did you get the equation:

    v= (pi/6)(3a^2 + 3b^2 + h^2) h?

    Is this segment from a hemi-sphere of base radius a, with a segment cut out of height h creating an upper face of radius b? If that's the case, then the volume would be expressed as

    v = pi ( a^2h - h^3)

    As to solving the cubic that you got for h, you can use a numerical technique like Newton's method to determine h. Or you can look into ways of solving cubics, from here:
    Cubic function - Wikipedia, the free encyclopedia

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