bell work find the surface area of the figure. 6 x 4 = 24 in² 3 x 4 = 12 in² 6 x 3= 18 in² add...
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Bell WorkFind the surface area of the figure.
6 x 4 = 24 in²
3 x 4 = 12 in²
6 x 3= 18 in²
Add them up!
SA = 24 + 24 + 12 + 12+ 18 + 18
SA = 108 in²
Surface Area Using the Formula
Surface Area•What does it mean to you?•Does it have anything to do with what is 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’s area!
Shortcut for surface Area
•You can find the SA of any prism by using the basic formula for SA which is:
SA= 2B + Ph•Ph = perimeter of the base x height•B = the area of the base of the prism.
Let’s start with a rectangular prism.
You can find the area for each surface and add them up, or surface area can be done using the formula.
SA = 2lw + 2lh + 2wh OR SA = 2B + Ph
Either method will give you the same answer.
Top/bottom 2(8)(4) = 64
Left/right 2(4)(7) = 56
Front/back 2(8)(7) = 112
Add them up!
SA = 232 cm²
Example: Find the area of each face
7 cm
4 cm
8 cm
SA= 2B + Ph
B = (7)(4) = 28
P = 4 + 4 + 7 + 7 = 22
h = 8
SA= 2(28) + 22(8)
SA= 56 + 176
SA = 232 cm²
OR
Example:
8mm
9mm
6 mm 6mm
Find the AREA of each SURFACE
1. Top and bottom triangle:
A = 2(½ bh)
A =2( ½ )(6)(6)
A = 36
2. The two sides are the same.
A = 2lw
A = 2(6)(9)
A = 108
3. The back rectangle is
different
A = lw
A = 8(9)
A = 724. ADD THEM ALL UP!
36+ 108+ 72
SA = 216 mm²
SA= 2B + Ph
SA= 2(18) + 20(9)
SA= 36 + 180
SA = 216 mm²
ORB = ( ½ )(6)(6) = 18
P = 6 + 6 + 8 = 20
h = 9
CubeAre all the faces the same? YES
4m
How many faces are there?
6
Find the Surface area of one of the faces.
4 x 4 = 16
Take that times the number of faces.X 6
96 m2
SA for a cube.
You try
SA= 2B + Ph
SA= 2(16) + 20(15)
SA = 32 + 300
SA= 332 in²
B = 2 x 8 = 16 in²P = 2 + 2 + 8 +8 = 20 in
Find the Surface Area
Practice
•Worksheet on Surface area