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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