Question

38. A right circular cone has
height 4 m and radius of the
base 3 m. Find its curved surface
area:
​

Answer 1

Given:-

• Height of right circular cone is 4m.
• Radius of right circular cone is 3m.

To find:-

• Curved surface area of cone.

Solution:-

We know that,

Curved surface area of cone = πrl

In which,

• r is Radius of cone.
• l is length of cone.

Length of cone is not given then, we know formula for length is

= $\sf \sqrt{ {(h)}^{2} + {(r)}^{2} }$

= $\sf \sqrt{ {(4)}^{2} + {(3)}^{2} }$

= 4 + 3

= 7

Length of cone is 7 cm.

Radius of cone is 3 cm.

Put the values of length and Radius in formula of Curved surface area

⇒π × 3 × 7

⇒22/7 × 3 × 7

⇒22 × 3

⇒66 cm²

Therefore,

Curved surface area of cone is 66 cm².