Find the surface area of spheres of the following radii.

(1)

(2)

(3)

(4)

(5)

(6)

(1). When given is radius of the sphere, r = 7 cm.

We have

Surface area of sphere is given by

Surface area = 4 πr²

Substituting the given value in the above equation, we get

Surface area = 4 × 22/7 × 7²

⇒ Surface area = (4 × 22 × 7 × 7)/7

⇒ Surface area = 616

Thus, surface area is 616 cm².

(2). When given is radius of the sphere, r = 10.5 cm.

We have

Surface area of sphere is given by

Surface area = 4 πr²

Substituting the given value in the above equation, we get

Surface area = 4 × 22/7 × (10.5)²

⇒ Surface area = (4 × 22 × 10.5 × 10.5)/7

⇒ Surface area = 9702/7 = 1386

Thus, surface area is 1386 cm².

(3). When given is radius of the sphere, r = 10 cm.

We have

Surface area of sphere is given by

Surface area = 4 πr²

Substituting the given value in the above equation, we get

Surface area = 4 × 3.14 × (10)²

⇒ Surface area = 4 × 3.14 × 100

⇒ Surface area = 1256

Thus, surface area is 1256 cm².

(4). When given is radius of the sphere, r = 2.8 cm.

We have

Surface area of sphere is given by

Surface area = 4 πr²

Substituting the given value in the above equation, we get

Surface area = 4 × 22/7 × (2.8)²

⇒ Surface area = (4 × 22 × 2.8 × 2.8)/7

⇒ Surface area = 689.92/7 = 98.56

Thus, surface area is 98.56 cm².

(5). When given is radius of the sphere, r = 9.8 m.

We have

Surface area of sphere is given by

Surface area = 4 πr²

Substituting the given value in the above equation, we get

Surface area = 4 × 22/7 × (9.8)²

⇒ Surface area = (4 × 22 × 9.8 × 9.8)/7

⇒ Surface area = 8451.52/7 = 1207.36

Thus, surface area is 1207.36 m².

(6). When given is radius of the sphere, r = 42 m.

We have

Surface area of sphere is given by

Surface area = 4 πr²

Substituting the given value in the above equation, we get

Surface area = 4 × 22/7 × (42)²

⇒ Surface area = (4 × 22 × 42 × 42)/7

⇒ Surface area = 155232/7 = 22176

Thus, surface area is 22176 m².