the diameter of the base of a right circular cone is 21 cm and it's Hight is 14 cm . it's curved surface area is
Answers
Answer:
Given :-
- The diameter of the base of a right circular cone is 21 cm and it's height is 14 cm.
To Find :-
- What is the curved surface area.
Formula Used :-
➦ Pythagoras Theorem :
★ (Slant Height)²=(Radius)² + (Height)² ★
➦ Curved Surface Area :
✧ Curved Surface Area = πrl ✧
where,
- r = Radius
- l = Slant Height
Solution :-
First, we have to find radius,
We know that,
✯ Radius = Diameter/2 ✯
Then,
↦ Radius = 21/2
➤ Radius = 10.5 cm
Again, we have to find the slant height,
Given :
- Radius = 10.5 cm
- Height = 14 cm
According to the question by using the formula we get,
⇒ (l)² = (10.5)² + (14)²
⇒ (l)² = 110.25 + 196
⇒ (l)² = 306.25
⇒ l = √306.25
➠ l = 17.5
Hence, the slant height is 17.5 cm
Now, we have to find the curved surface area of a cone,
Given :
- Radius = 10.5 cm
- Slant Height = 17.5 cm
According to the question by using the formula we get,
⇒ C.S.A of cone = 22/7 × 10.5 × 17.5
⇒ C.S.A of cone = 22/7 × 183.75
➠ C.S.A of cone = 577.5 cm²
∴ The curved surface area of cone is 577.5 cm² .
Answer:
Its curved surface area = 577.5 cm²
Step-by-step explanation:
Given that:
- The diameter of the base of a right circular cone is 21 cm then Radius = 21/2 = 10.5 cm
- And its height is 14 cm
To find:
- Its curved surface area.
Formula used:
Curved surface of right circular cone = πr√(r² + h²) sq. unit
Finding the curved surface area:
Curved surface area = π × 10.5 × √(10.5² + 14²) cm²
Curved surface area = π × 10.5 × √(110.25 + 196) cm²
Curved surface area = π × 10.5 × √(306.25) cm²
Curved surface area = π × 10.5 × 17.5 cm²
Curved surface area = (22 × 10.5 × 17.5)/7 cm²
Curved surface area = 577.5 cm²