Surface Area
• What does it mean to you?
• Does it have anything to do with what is in
the inside of the prism.?
• Surface area is found by finding the area of
all the sides and then adding those answers
up.
• How will the answer be labeled?
• Units2 because it is area!
Rectangular Prism
B
5
in
A
How many faces are
on here? 6
C
6
4
A = 5 x 4 = 20 x 2 =40
B = 6 x 5 = 30 x 2 = 60
C = 4 x 6 = 24 x 2 = 48
148 in2
Find the area of each of
the faces.
Do any of the faces
have the same area?
If so, which ones?
Opposite faces are the same.
Find the SA
Cube
A
Are all the faces the same?
4m
How many faces are
there?
YES
6
Find the Surface area of
one of the faces.
4 x 4 = 16
X6
96 m2
Take that times the
number of faces.
SA for a cube.
Triangular Prism
4
How many faces are
there? 5
5
How many of each shape does it
take to make this prism?
10
m
3
2 triangles and 3 rectangles = SA of a
triangular prism
Find the surface area. Start by
x 2= 12
4 x 3/2 = 6
finding the area of the triangle.
How many triangles were
there? 2
5 x 10 = 50 = front
Find the area of the 3
rectangles.
3 x 10 = 30 = bottom
What is the final SA?
4 x 10 = 40 = back
SA =
132 m2
SA
• You can find the SA of any prism by using
the basic formula for SA which is
• 2B + LSA= SA
• LSA= lateral Surface area
• LSA= perimeter of the base x height of the
prism
• B = the base of the prism.
Triangular Prisms
• Use the same triangular prism we used before.
Let’s us the formula this time. 2B + LSA=SA
• Find the area of the base, which is a triangle
because it is a triangular prism. You will need two
of them.
• Now, find the perimeter of that same base and
multiply it by how many layer of triangles are in
the picture. That is the LSA.
• Add that to the two bases. Now you should have
the same answer as before.
• Either way is the correct way.
Cylinders
6
2B
What does it take to make this?
10m
2 circles and 1 rectangle= a cylinder
2B + LSA = SA
3.14 x 9 = 28.26 X 2 = 56.52
+ LSA(p x H)
3.14 x 6 =18.84 x 10 = 188.4
SA =
244.92
Why should you learn about surface area?
Is it something that you will ever use in
everyday life?
If so, who do you know that uses it?
Have you ever had to use it outside of
math?