for each circle c, find the value of x. assume that segments that appear to be tangent are. (4 pts...
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C
x4
8
A
B
C
D
7x - 2
3x + 8
For each circle C, find the value of x. Assume that segments that appear to be tangent are. (4 pts each)
1. 2. 3.
C
8x
12
x
KT
c
c
b
EOCT Practice
Question of the Day
Math IIDay 39 (10-6-10)
UNIT QUESTION: What special properties are found with the parts of a circle?Standard: MM2G1, MM2G2
Today’s Question:What effect does changing the radius have on S.A. and Volume of a sphere?Standard: MM2G4.a,b
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.
Formulas for a Sphere2
3
4
4
3
SA r
V r
8 in
Surface Area of a Sphere(round to the nearest hundredths)
SA4 r2
SA4 82
SA804.25 in2
10 cm
Surface Area of a Sphere(round to the nearest hundredths)
SA4 r2
SA4 52
SA31416. cm2
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
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
5 in
SA and Volume of a SphereA spherical balloon has a surface area of 16 in.2 Find the volume of the sphere.
26.02 inV
10 in
34
3V rSA4 r2
5 in
Volume of a SphereA sphere has an initial volume of 400 cm.3 The sphere is made bigger by making the radius 4 times as big. What is the new volume of the sphere?
225,600 inV
10 in
34
3V r
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