Question

Surface area of a sphere whose diameter 70 cm

Answer 1

Given :

• Diameter of a sphere = 70 cm

To find :

• Surface area of a sphere

Concept :

Here, we have to find the surface of sphere. So, for that we need the value of radius. Firstly we will calculate the radius of the sphere. Then by using the formula to find the surface area of sphere we will get our required answer.

The commonly used units for area are m² and cm².

Formula to find radius, when diameter is given :-

• Radius = D ÷ 2

Formula to find surface area of sphere :-

• Surface area of sphere = 4πr²

where,

• Take π = 22/7

• D denotes the diameter of the sphere

• r denotes the radius of the sphere

Solution :

Calculating the radius of the sphere :-

→ Radius = Diameter ÷ 2

→ Substituting the given values :-

→ Radius = 70 ÷ 2

→ Radius = 35

Radius of the sphere = 35 cm

Now, calculating the surface area of sphere :-

→ Surface area of sphere = 4πr²

→ Substituting the given values :-

→ Surface area of sphere = 4 × 22/7 × (35)²

→ Surface area of sphere = 4 × 22/7 × 35 × 35

→ Surface area of sphere = 4 × 22 × 5 × 35

→ Surface area of sphere = 15,400

Therefore, the surface area of sphere = 15,400 cm²