Daily Check

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Daily Check
For each circle C, find the value of x. Assume
that segments that appear to be tangent are. (4
pts each) 1. 2. 3.
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EOCT Practice 1
c
3
EOCT Practice 2
c
4
EOCT Practice 3
b
5
EOCT Practice
Question of the Day
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Math IIDay 39 (10-6-10)
UNIT QUESTION What special properties are found
with the parts of a circle? Standard MM2G1,
MM2G2 Todays Question What effect does
changing the radius have on S.A. and Volume of a
sphere? Standard MM2G4.a,b
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6.9 Surface Area of Spheres
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Radius of a Sphere
r
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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.
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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.
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Formulas for a Sphere
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Surface Area of a Sphere (round to the nearest
hundredths)
8 in
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Surface Area of a Sphere (round to the nearest
hundredths)
10 cm
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The circumference of a great circle of a sphere
is 25 inches. Find the surface area of the
sphere. (Round to the nearest tenths.)
25 in
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Surface Area of a Sphere A 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.
10 in
5 in
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6.9 Volume of Spheres
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Volume of a Sphere (round to the nearest
hundredths)
2 cm
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Volume of a Sphere
10 cm
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Volume of a Sphere A 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.
10 in
5 in
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SA and Volume of a Sphere A spherical balloon has
a surface area of 16 in.2 Find the volume of the
sphere.
10 in
5 in
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Volume of a Sphere A 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?
10 in
5 in
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Class work Test Prep Workbook Page 38
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Homework Page 239 1-18