5.5 "Cone Lateral Area"
The lateral (side) surface area does NOT include base area
TOTAL surface area = lateral surface area + base area
The lateral surface area does NOT include base area
TOTAL surface area = lateral surface area + base area
Lateral
Surface
Area
?
Base
(circle)
Area
?
The cone HEIGHT (h) forms a right angle with the base
The SLANT HEIGHT (t) runs along the side of the cone
height
?
slant height
?
radius
?
Lateral (side) SA =  (π) x  (radius)  x  (slant height)
8
6
10
π
x
x
π square units
Lateral (side) SA =  (π) x  (radius)  x  (slant height)
12
5
13
π
x
x
π square units
Lateral (side) SA =  (π) x  (radius)  x  (slant height)
4
3
Use the PYTHAGOREAN THEOREM
to find the slant height
(it's a Pythagorean TRIPLE)
Lateral (side) SA =  (π) x  (radius)  x  (slant height)
4
3
5
π
x
x
π
π square units
Lateral (side) SA =  (π) x  (radius)  x  (slant height)
12
5
Use the PYTHAGOREAN THEOREM
to find the slant height
(it's a Pythagorean TRIPLE)
Lateral (side) SA =  (π) x  (radius)  x  (slant height)
12
5
13
π
x
x
π
π square units
Find the slant height of these cones (use pythagorean thm)
8
6
12
5
24
10
Which cone
is the
tastiest?
(that's right)
.
.
.
The
End
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