A right angle triangle whose sides are 15 cm and 8 cm is made to revolve around its perpendicular (i.e. 15 cm long). Find the curved surface area of the cone formed.

427.04 cm²

The perpendicular becomes height and base becomes radius

⇒ Hypotenuse = slant height = \(\sqrt {15^2 + 8^2}\)

= \(\sqrt {225 + 64}\) = = \(\sqrt {289}\) = 17 cm

C.S.A. of cone = \(\pi \)rl

                     = 3.14 × 8 × 17 = 427.04 cm²