Warm up Find the circumference of the circle with a sector area of 16 28.75.

Warm up

Find the circumference of the circle with a sector area of 16

28.75

Warm up (again)

Find the area of the circle given the arc length of 16

732.5

r

Radius of a Sphere

If you cut a sphere right down the middle you would create two congruent halves called HEMISPHERES.

You can think of the globe. The equator cuts the earth into the northern and southern

hemisphere.

Look at the cross section formed when you cut a sphere in half.

What shape is it?

A circle!!! This is called the GREAT CIRCLE of the sphere.

Surface Area of a Sphere24SA r

8 in

Surface Area of a Sphere(round to the nearest hundredths)

SA4 r2

SA4 82

SA804.25 in2

SA = 256π

10 cm

Surface Area of a Sphere(round to the nearest hundredths)

SA4 r2

SA4 52

SA31416. cm2

SA = 100π

25 in

The circumference of a great circle of a sphere is 25 inches. Find the surface area of the sphere. (Round to the nearest tenths.) C 2 r

3.979r 24 (3.979)SA

25 2 r

2198.96SA in

5 in

Surface Area of a SphereA spherical balloon has an initial radius of 5 in. When more air is added, the radius becomes 10 in. Explain how the S.A. changes as the radius changes.SA4 r2

2 2314.16 in .1,256.64 inSA vs

10 in

? in

Find the radius

SA4 r2

2804.25 4 r2804.25

r4

264 r8 r804.25SA

? cm

Find the diameter

SA4 r2

2100 4 r 2100

r4

225 r5 r10 d100SA

Volume of a Sphere

34

3V r

2 cm

Volume of a Sphere(round to the nearest hundredths)

34

3V r

V 3351. cm3

34 2

3V

10 cm

Volume of a Sphere

V 523 60. cm3

34

3V r

34 5

3V

5 in

Volume of a SphereA spherical balloon has an initial radius of 5 in. When more air is added, the radius becomes 10 in. Explain how the volume changes as the radius changes.

2 2523.6 in . 4,118.8 inV vs

10 in

34

3V r

? cm

Find the radiusV

r

( )4

3

3

3(4 r )33.51

3

V 3351. cm3

3(4 r )3 33.51x

3100.53r

4

38 r2 r

? cm

Find the diameterV

r

( )4

3

3

3(500 ) (4 r )

3 3

3(500 ) cm

3V

3(4 r )500

3500r

4

3125 r5 r 10 d