The height and radius of cone are 4 cm and 3 cm respectively. Fnd the curved surface area of cone.
15π cm2
Given, height of the cone, h = 4 cm
radius of the cone, r = 3 cm
As we revolve a right-angled triangle about its height, we will get a cone. Therefore, slant height is the hypotenuse of the corresponding right-angled triangle.
By using Pythagoras' theorem, we get,
Slant height, l=√h2+r2 =√42+32 =5 cm
Surface area of the cone = πrl
= π ×3 × 5
= 15π cm2