Answer: A
Let the radius of the base of the cone be \(r\) cm. \(\therefore \cfrac{1}{3}\pi r^2 \times 12 = 1024\pi\) Or, \(r^2 = \cfrac{1024 \times 3}{12} = 256\) \(\therefore r = 16\) \(\therefore\) Slant height = \(\sqrt{12^2 + 16^2}\) cm \(= \sqrt{144 + 256}\) cm \(= \sqrt{400}\) cm \(= 20\) cm
Let the radius of the base of the cone be \(r\) cm. \(\therefore \cfrac{1}{3}\pi r^2 \times 12 = 1024\pi\) Or, \(r^2 = \cfrac{1024 \times 3}{12} = 256\) \(\therefore r = 16\) \(\therefore\) Slant height = \(\sqrt{12^2 + 16^2}\) cm \(= \sqrt{144 + 256}\) cm \(= \sqrt{400}\) cm \(= 20\) cm