3.5 Surface Area of a Rectangular Prism

Mme DiMarco

Learning Goal: use a formula to calculate the surface area of a rectangular prism

Learning Goal

Formulas:

Rectangle: A = b x hP = 2 x (b + h)

Square:A = c2

P = 4c

Remember!

b

h

s

s

Flat representation of all the faces of a polyhedron

Each face is connected to at least one other by a common edge

Net of a Polyhedron

Surface area = the sum of the areas of each individual rectangle (the total area of the net)

Surface area of a rectangular prism

3cm

8cm

5cm

Area = 8 x 5

Area = 8 x 3

Area = 8 x 5

Area= 8 x 3

Area

= 5

x

3

8cm 3cm

5cm

3cm

5cm

Area

= 5

x

3

3cm

5cm

3cm

Step 1: find the area for each individual face on the rectangular prismStep 2: add each area to find the total area

We can do both of these steps in one equation…

At = 2(8 x 3) + 2(8 x 5) + 2(3 x 5)At = 2(24) + 2(40) + 2(15)At = 48 + 80 +30 At = 158cm2

Surface area of a rectangular prism

You can write the equation

A variable represents each letter… Length = l Width = w Height = h

Formula for area of a rectangular prism

Aire = L x l

Aire = L x h

Aire = L x l

Aire = L x h

Aire

= l

x h

hL

l

wh

l

h

h

l

Aire

= l

x h

At = 2lh + 2lw + 2hw

Page 99, questions 1 à 3

Homework