Find the area of metal sheet required in making a closed hollow cone of base radius 7 cm and height 24 cm.
We have,
Base radius of cone = 7 cm
Height of cone = 24 cm
Slant height of cone l = √( r2+h2) = √(242+72) = √625 = 25 cm
Hence area of metal sheet required = total surface area of cone
= πr(l+r) = 22/7 ×7 (25+7)
=704 cm2