SURFACE AREAS OF SPHERES

Surface Area of a Sphere

Find the surface area of the sphere. Round to the nearest tenth.

S = 4r2 Surface area of a sphere

= 4(4.5)2 Replace r with 4.5.

≈ 254.5 Simplify.

Answer: 254.5 in2

A. 462.7 in2

B. 473.1 in2

C. 482.6 in2

D. 490.9 in2

Find the surface area of the sphere. Round to the nearest tenth.

Use Great Circles to Find Surface Area

A. Find the surface area of the hemisphere.

Find half the area of a sphere with the radius of 3.7 millimeters. Then add the area of the great circle.

Use Great Circles to Find Surface Area

Surface area of a hemisphere

Answer: about 129.0 mm2

Replace r with 3.7.

Use a calculator.≈ 129.0

Use Great Circles to Find Surface Area

B. Find the surface area of a sphere if the circumference of the great circle is 10 feet.

First, find the radius. The circumference of a great circle is 2r. So, 2r = 10 or r = 5.

Use Great Circles to Find Surface Area

Answer: about 314.2 ft2

S = 4r2 Surface area of a sphere

= 4(5)2 Replace r with 5.

≈ 314.2 Use a calculator.

Use Great Circles to Find Surface Area

C. Find the surface area of a sphere if the area of the great circle is approximately 220 square meters.

First, find the radius. The area of a great circle is r2. So, r2 = 220 or r ≈ 8.4.

Use Great Circles to Find Surface Area

Answer: about 886.7 m2

S = 4r2 Surface area of a sphere

≈ 4(8.4)2 Replace r with 5.

≈ 886.7 Use a calculator.

A. 110.8 m2

B. 166.3 m2

C. 169.5 m2

D. 172.8 m2

A. Find the surface area of the hemisphere.

A. 100.5 ft2

B. 201.1 ft2

C. 402.2 ft2

D. 804.3 ft2

B. Find the surface area of a sphere if the circumference of the great circle is 8 feet.

A. 320 ft2

B. 440 ft2

C. 640 ft2

D. 720 ft2

C. Find the surface area of the sphere if the area of the great circle is approximately 160 square meters.