Total Surface Area of Cone | Exercise 13.3 Q3

Question 3: Curved surface area of a cone is 308 cm² and its slant height is 14 cm. Find
(i) radius of the base and
(ii) total surface area of the cone

Explanatory Answer | Exercise 13.3 Q3

Part (i): Find the radius of the base of the cone

Curved surface area of cone = π × r × l = 308 cm².
Slant height of the cone, l = 14 cm
Take π =\\frac{22}{7})
So, \\frac{22}{7}) × r × 14 = 308
r = \\frac{308 × 7}{22 × 14})
Radius of the cone, r = 7 cm

Part (ii): Find the Total Surface Area of Cone

Total surface area of the cone = π × r ×(l + r)
= \\frac{22}{7}) × 7 × (14 + 7)
=\\frac{22}{7}) × 7 × 21
= 462 cm²

Exercise 13.1 | Surface Area of Cubes & Cuboids

1. Class 9 Exercise 13.1 Question 3 | Height of hall ▶
2. Class 9 Exercise 13.1 Question 6 | TSA of Herbarium ▶
3. Class 9 Exercise 13.1 Question 7 | Shanti Sweets ▶

Exercise 13.2 | Surface Area of Cylinders

1. Class 9 Exercise 13.2 Question 3 | CSA TSA of Metal Pipe ▶
2. Class 9 Exercise 13.2 Question 4 | Roller & Playground ▶
3. Class 9 Exercise 13.2 Question 9 | Cylindrical Petrol Tank ▶
4. Class 9 Exercise 13.2 Question 10 | CSA of Decorative Lampshade ▶

Exercise 13.3 | Surface Area of Cones

1. Class 9 Exercise 13.3 Question 5 | Length of Tarpaulin 3 m wide ▶
2. Class 9 Exercise 13.3 Question 8 | Cost of painting conical barricades ▶

Exercise 13.4 | Surface Area of Spheres & Hemispheres

1. Class 9 Exercise 13.4 Question 8 | Outer CSA of hemispherical bowl ▶
2. Class 9 Exercise 13.4 Question 9 | Surface area of sphere & Cylinder ▶