In this page curved surface area solution7 we are going to see solution of some practice questions.

**Question 14**

The central angle and radius of a sector of a circular disc are 180 degree and 21 cm respectively. If the edges of the sector are joined together to make a hollow cone,then find the radius of the cone.

**Solution:**

**Solution:**

The cone is being created by joining the radius. So the radius of the sector is going to be the slant height of the cone.

Slant height (L) = 21 cm

Arc length of the sector = Circumference of the base of the cone

Length of arc = (θ/360) **x **2Π R

Here R represents radius of the sector

= (180/360) **x **2** x ** (22/7)**x ** (21)

= (1/2) **x **2** x **22**x **3

= 66 cm

So,circumference of the base of the cone = 66

2 Π r = 66

2 **x ** (22/7)** x** r = 66

r = 66 **x** (1/2) **x** (7/22)

r = 10.5 cm

**Question 15**

Radius and slant height of a solid right circular cone are in the ratio 3:5. If the curved surface area is 60 Π cm², then find its total surface area.

**Solution:**

Radius and slant height of a solid right circular cone are in the ratio 3:5.

r : L = 3 : 5

r/L =3/5

r = 3L/5

Curved surface area of cone = 60 Π cm²

Π r L = 60 Π

Π **x** (3L/5) **x** L = 60 Π

L² = 60 **Π x** (1/Π) **x** (5/3)

L² = 60 **x** (5/3)

L² = 100

L = 10

r = 3(10)/5

r = 6

Total surface area = Π r (L + r)

= Π (6) (10 + 6)

= 96 Π cm²

**Total surface area of cone = 96 Π cm² **

curved surface area solution7 curved surface area solution7

- Back to worksheet

- Area
- Curved Surface Area
- Total Surface Area
- Volume
- Cylinder
- Conoid (Cone)
- Sphere
- Problems on Curved Surface Area
- Problems on Total Surface Area
- Problems on Volume
- Formulas For Shapes
- Perimeter of Sector
- Perimeter of Sector Worksheets
- Length of Arc
- Practice questions on length of arc
- Perimeter of square
- Perimeter of Parallelogram
- Perimeter of Rectangle
- Perimeter of a Triangle
- Area of a Circle
- Area of Semicircle
- Area of Quadrant
- Area of a Sector
- Area of a Triangle
- Area of Equilateral Triangle
- Area of Scalene Triangle
- Area of Square
- Area of Rectangle
- Area of Parallelogram
- Area of Rhombus
- Area of Trapezium
- Area of Quadrilateral
- Area Around Circle
- Path Ways
- Combined Figures