// JavaScript Document
function TankVol()
{
var Tank = document.getElementById('tank');
var DFeet = Tank.DiaFeet.value + Tank.DiaInches.value
  var LFeet = Tank.LengthFeet.value + Tank.LengthInches.value 
  var Pi = 3.14159
  var Radius = DFeet/2
  var Gallons = Math.round(Radius*Radius*Pi*LFeet*7.5)

Tank.Volume.value = Gallons

var PFeet = Tank.ProdFeet.value + Tank.ProdInches.value
  var Seg1 = Radius*Radius*Pi/2
  var x = Radius - PFeet
  var Seg2 = (Radius*Radius)-(x*x)
  var Seg3 = Math.sqrt(Seg2)
  //sqrt(r^2-x^2)
  var Arcsine = Math.asin(x/Radius)
  //sin^-1(x/r)
  var Seg4 = Radius*Radius*Arcsine
  var Seg5 = x*Seg3
  var SegSF = Seg1 - (Seg4 + Seg5)
  var Gallons2 = Math.round(SegSF*LFeet*7.5)
  
var PFeet2 = DFeet - PFeet
  var Seg1 = Radius*Radius*Pi/2
  var x = Radius - PFeet2
  var Seg2 = (Radius*Radius)-(x*x)
  var Seg3 = Math.sqrt(Seg2)
  //sqrt(r^2-x^2)
  var Arcsine = Math.asin(x/Radius)
  //sin^-1(x/r)
  var Seg4 = Radius*Radius*Arcsine
  var Seg5 = x*Seg3
  var SegSF = Seg1 - (Seg4 + Seg5)
  var Air = Math.round(SegSF*LFeet*7.5)
    
  var Gallons3 = Gallons - Air

if (PFeet>Radius)Tank.ProdVolume.value = Gallons3
  else Tank.ProdVolume.value = Gallons2
}

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