Transcript Volume Rectangular Prisms

Volumes of Rectangular Prisms
and Cylinders
Lesson 9-9
Vocabulary
• The volume of a three-dimensional
figure is the number of cubic units
needed to fill the space inside the
figure.
• A cubic unit is a cube that
measures 1 unit long, 1 unit wide,
and 1 unit high.
Counting Cubes
• If the figure is split into
cubes already, then just
count the cubes in one
layer and multiply that by
the number of layers.
The top layer is 4 x 5, or 20 cubic units.
There are 20 cubic units per layer, times 3
layers, for a volume of 60 cubic units.
Using Formulas
• To find the volume of a rectangular prism
or a cylinder, multiply the area of the base
by the height.
• Volume = Area of Base x height
• V = Bh
• (The capital B does not stand for base, it
stands for area of the base.)
Volume of a Rectangular
Prism
V = Bh
In this case, the
base is a rectangle.
The area formula for
a rectangle is l x w.
V = (l x w) x h
V = (4 x 3) x 12
V = 144 cm3
Volume gives us cubic units.
Volume of a Cylinder
V = Bh
5 in
In this case, the
base is a circle.
The area formula
for a circle is r2
16 in
V = (r2) x h
V = (3.14)(52)(16)
V = (3.14)(25)(16)
V = 1,256 in3
Homework Time
V=lwh