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.
Answer & explanation
Correct answer: option 2
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