Transcript Slide 1

Homework
Find the surface area of each figure to the
nearest tenth. Use 3.14 for p.
1. the cone
Find the surface area of each sphere, both in
terms of p and to the nearest tenth. Use 3.14
for p.
2. r = 22 in
3. d = 1.5 mi
Warm Up
A cylindrical can has a diameter of 14 cm and a
height of 20 cm. What is the surface area to the
nearest tenth? Use 3.14 for p.
1186.9 cm2
Vocabulary
slant height
right cone
great circle
The slant height of a cone is
measured along its lateral
surface.
Right cone
In a right cone, a line perpendicular to the
base through the vertex passes through the
center of the base.
Check It Out! Example 1
Find the surface area of each figure to the
nearest tenth. Use 3.14 for p.
S = pr2 + prl
=
p(72)
+ p(7)(18)
= 175p  549.5
ft2
18 ft
7 ft
A sphere is the set of points in three
dimensions that are a fixed distance from
a given point, the center.
A plane that intersects a sphere through
its center divides the sphere into two
halves or hemispheres. The edge of a
hemisphere is a great circle.
The surface area of a sphere is four times
the area of a great circle.
Additional Example 2: Finding Surface Area of a
Sphere
Find the surface area, both in terms of p
and to the nearest tenth. Use 3.14 for p.
S = 4pr2
= 4p(32)
Surface area of a sphere
Substitute 3 for r.
= 36p in2  113.0 in2
Check It Out! Example 2
The moon has a radius of 1738 km. Find
the surface area, both in terms of p and to
the nearest tenth. Use 3.14 for p.
S = 4pr2
= 4p(17382)
Surface area of a sphere
Substitute 1738 for r.
= 12,082,576p km2
 37,939,288.6 km2
1738 km
Homework Solutions
Find the surface area of each figure to the
nearest tenth. Use 3.14 for p.
1. the cone
175.8 in2
Find the surface area of each sphere, both in
terms of p and to the nearest tenth. Use 3.14
for p.
2. r = 22 in
3. d = 1.5 mi
1936p in2, 6079.0 in2
2.25p mi2, 7.1 mi2