Question

Diameter of the base of a cone is 10.5 cm and its slant height is 10 cm. Find its curved surface area.​

Answer 1

Right circular cone:

If a right angled triangle is revolved about one of the two sides forming a right angle keeping the other side fixed in position then the solid so obtained by segments is called right circular cone.

Slant height:

The length of the line segment joining the vertex to any point on a circular edge of the base is called the slant height of the cone.

Given: Diameter= 10.5 cm Radius (r) =$\sf \dfrac \pink{10.5}{2}$cm = 5.25 cm

Slant height (I) = 10 cm

Curved surface area of the cone = (πrl)

=($\sf \dfrac{22}{7}$x 5.25 × 10)

$\sf \pink{=165 cm²}$

Hence, the curved surface area of a cone=165cm²

Answer 2

Answer:

Given :-

Diameter of the cone = 10.5 cm

Radius, r = d/2 = 10.5/2 = 5.25 cm

Slant height of the cone, l = 10 cm

Curved surface area of the cone = rl

$:\longmapsto$ (22/7) × 5.25 × 10

$\sf :\longmapsto \pink{165 cm²}$

Hence the curved surface area of the cone is 165 cm².