how to find slant height with surface area?
['Volume of a cone: V = (1/3)πr2h.', 'Slant height of a cone: s = √(r2 + h2)', 'Lateral surface area of a cone: L = πrs = πr√(r2 + h2)', 'Base surface area of a cone (a circle): B = πr. ... ', 'Total surface area of a cone: A = L + B = πrs + πr2 = πr(s + r) = πr(r + √(r2 + h2))']