Question 1156080


{{{A = 2pi*r^2 + 2pi*hr}}}

solve for {{{r}}}

{{{A = 2pi(r^2 + hr)}}}

{{{A/2pi=r^2 + hr}}}.......complete square

{{{A/2pi=(r^2 + hr+b^2)-b^2}}}.....{{{b=h/2}}}

{{{A/2pi=(r^2 + hr+(h/2)^2)-(h/2)^2}}}

{{{A/2pi=(r+h/2)^2-h^2/4}}}

{{{A/2pi+h^2/4=(r+h/2)^2}}}

{{{sqrt(A/2pi+h^2/4)=r+h/2}}}

{{{r=sqrt(A/2pi+h^2/4)-h/2}}}