



 
Hi Jazmin, Substituting the known values into the expression you have for the surface area gives \[2 \pi r^2 + 2 \pi r \times 0.8 = 143.7.\] Taking out a common factor of $2 \pi$ gives \[2 \pi \left(r^2 + 0.8 r \right) = 143.7.\] Divide both sides by $2 \pi$ and then transfer the constant to the left side of the equation to yield a quadratic equation of the form \[a r^2 + br + c = 0.\] Use the general quadratic formula to solve for $r.$ You should obtain two values for $r$ but you know that $r$ must be positive. Penny  


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