Question

A cone resting on its base, with a dashed line from the side of the circle to the center of the circle labeled r. The edge of the cone is labeled Slant height (l).
The surface area of a cone is given by the formula
S = πrl + πr2. Solve the formula for l.

l = S – r2
l = S + r2
l =
l =

Answer 1

Start with S = πrl + πr^2.

Subtract πr^2: S − πr^2 = πrl.

Divide by πr: l = (S − πr^2)/(πr) = S/(πr) − r.