Question

Find volume & surface area of right circular cone whose base radius is 7 cm & hight 15 cm.​

Answer 1

Given :

• Radius of a right circular cone = 7 cm
• Height of a right circular cone = 15 cm

To find :

• Volume of the circular cone
• Surface area of the right circular cone

Knowledge required :-

→ Formula of the volume of right circular cone :-

• Volume = πr²h/3

→ Formula of the surface area of right circular cone :-

• Surface area = πr(r + √(h² + r²))

where,

• Take π = 22/7
• r = radius
• h = height

Solution :

Volume of the right circular cone :-

⇒ Volume = πr²h/3

⇒ Volume = 22/7 × (7)² × 15/3

⇒ Volume = 22/7 × 7 × 7 × 15/3

⇒ Volume = 22 × 7 × 5

⇒ Volume = 770

$\red\bigstar \underline{ \pmb{Volume~~ of~~ the~~ right~~ circular ~~cone ~~=~~ 770~~ cm^3}}$

Surface area of the right circular cone :-

⇒ Surface area = πr(r + √(h² + r²))

⇒ Surface area = 22/7 × 7(7 + √(15)² + √(7)²

⇒ Surface area = 22(7 + √(225 + 49))

⇒ Surface area = 22(7 + √274)

⇒ Surface area = 22(7 + 16.55)

⇒ Surface area = 22(23.55)

⇒ Surface area = 518.1

$\red\bigstar \underline{ \pmb{Surface~~ area ~~of~~ the~~ right~~ circular ~~cone ~~= ~~518.1 ~~cm^2}}$

Answer 2

Given :

• Radius of a right circular cone = 7 cm
• Height of a right circular cone = 15 cm
• To find :
• Volume of the circular cone
• Surface area of the right circular cone Knowledge required :-

→ Formula of the volume of right circular cone :-

Volume = πr²h/3

→ Formula of the surface area of right circular cone :-

Surface area = πr(r + √(h² + r²))

where,

Take π = 22/7

r = radius

h = height

Solution :

Volume of the right circular cone :-

⇒ Volume = πr²h/3

⇒ Volume = 22/7 × (7)² × 15/3

⇒ Volume = 22/7 × 7 × 7 × 15/3

⇒ Volume = 22 × 7 × 5

⇒ Volume = 770

$\red\bigstar \underline{ \pmb{Volume~~ of~~ the~~ right~~ circular ~~cone ~~=~~ 770~~ cm^3}}★$

Volume of the right circular cone = 770 cm

3

Volume of the right circular cone = 770 cm

3

Surface area of the right circular cone :-

⇒ Surface area = πr(r + √(h² + r²))

⇒ Surface area = 22/7 × 7(7 + √(15)² + √(7)²

⇒ Surface area = 22(7 + √(225 + 49))

⇒ Surface area = 22(7 + √274)

⇒ Surface area = 22(7 + 16.55)

⇒ Surface area = 22(23.55)

⇒ Surface area = 518.1

★ Surface area of the right circular cone

= 518.1cm²