The surface area of a cone is given by the formula:
S = πl + πr^2
Solving for l, we can start by isolating l on one side of the equation:
S - πr^2 = πl
Dividing both sides by π:
(S - πr^2) / π = l
Therefore, the length l can be found by subtracting the product of π and r^2 from the surface area S, and dividing the result by π.