The curved surface area of a right circular cone of radius 7 cm is 220 cm2. What is the height of the cone?
1. √22
2. √47
3. √51
4. √61
The curved surface area of a right circular cone of radius 7 cm is 220 cm2. What is the height of the cone?
1. √22
2. √47
3. √51
4. √61
1. √22
2. √47
3. √51
4. √61
Correct Answer – Option 3 : √51
Given:
Radius of cone = 7 cm
Curved surface area of cone = 220 cm2
Formula used:
Curved surface area of cone = πrl
Where, r = radius of cone
l = slant height of cone
h = height of cone
l2 = r2 + h2
Calculation:
220 = π × 7 × l
⇒ l = 220/22 = 10 cm
Also,
102 = 72 + h2
⇒ h2 = 100 – 49 = 51
⇒ h = √51 cm
∴ The height of the cone is √51 cm.