Question 157294
Remember: {{{Area[c]=2(pi)(r^2)+2(pi)(r)(h)}}} ------> working eqn
Substitute:
{{{(96cm^2)(pi)=2(pi)(r^2)+2(pi)(r)(8)}}}
{{{cross(96)48*cross(pi)/(cross(2*pi))=cross(2*pi)*r(r+8)/cross(2*pi)}}}
{{{48=r^2+8r}}}
{{{r^2+8r-48=0}}}, factor out, perfect square:
{{{(r+12)(r-4)=0}}}
2 values: {{{r=-12}}} ------------> don't use, (-)
{{{r=4cm}}} ----------------------> RADIUS, to be used
In doubt? go back working eqn:
{{{(96)pi=2(pi)(4^2)+2(pi)(4)(8)}}}
{{{(96)pi=32(pi)+64(pi)}}}
{{{(96)pi=(96)pi}}}
Thank you,
Jojo