Question 177916
{{{V=2(pi)r^2 + 2(pi)r*h}}}--->remember r=R
:
{{{3V=2(pi)R^2 + 2(pi)R*H}}}
:
in order for these 2 equations to be equal we have to multiply the smaller Volume by 3
:
:
{{{3(2(pi)R^2 + 2(pi)R*h)=(2(pi)R^2 + 2(pi)R*H)}}}
:
{{{6(pi)R(R+h)=2(pi)R(R+H)}}}factoring {{{6(pi)R}}} on left and {{{2(pi)R}}}on the right 
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{{{3(R+h)=R+H}}}divided both sides by {{{2(pi)R}}}
:
{{{3R+3h=R+H}}}distributed left side
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{{{2R=H-3h}}}subtracted R and 3h from both sides
:
{{{highlight(R=(H-3h)/2)}}}....divided both sides by 2