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1 Finding Surface Area Step 1: Flatten the 3-D figure A rectangular prism will flatten to 6 rectangles. Depending on the dimensions of the 3-D figure, you will have different size rectangles. Rectangular Prism

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2 Finding Surface Area Step 2: Transfer the dimensions to the 3-D figure Dimensions: Length – 12 (left to right) Height – 8 (top to bottom) Width – 4 (front to back) Rectangular Prism Height 8 Length 12 Width 4

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3 Finding Surface Area Step 3: Transfer the dimensions from the 3-D figure to the flattened figure Dimensions: Length – 12 (the longest side) Height – 8 (top to bottom) Width – 4 (front to back) Rectangular Prism Height 8 Length 12 Width

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4 Finding Surface Area Step 4: Find the AREA for each rectangle. (Length X Width) Rectangular Prism Height 8 Length 12 Width x 4 12 x 8 12 x 4 12 x 8 8 x 4 48 sq units 96 sq units 48 sq units 96 sq units32

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5 Finding Surface Area Step 4: Find the TOTAL SURFACE AREA for the 3-D Figure Add together the areas for each rectangle Rectangular Prism sq units 96 sq units 48 sq units 96 sq units = 352 sq. units Total surface area

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6 You can also use a table, instead of drawing the net Since opposite faces are congruent, you have three pairs of congruent rectangles. FaceFormula: A = bhArea Top4 x 1248 Bottom4 x 1248 Left8 x 432 Right8 x 432 Front8 x 1296 Back8 x 1296 Total: 352 sq units

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7 Group Practice: Fill out this table on your scratch paper to find the area for this figure. FaceFormula: A = bhArea Top Bottom Left Right Front Back Total: _____ sq units

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8 CPS Practice : The top and bottom faces each have an area of: A) None of the above (Fill out a table for this figure as you do each of the next few questions.)

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9 The left and right faces each have an area of: A) None of the above

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10 The front and back faces each have an area of: A) None of the above

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11 The total surface area of this rectangular prism is: A) 765 B) 896 C) 344 D) 688

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12 Cube or Square A cube or square will flatten to 6 equal squares.

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13 Triangular Prism A triangular prism will flatten to 3 rectangles and two equal triangles. Step 1: Flatten the 3-D figure

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14 Triangular Prism Step 2: Transfer the dimensions to the 3-D Figure Dimensions: Base = 8 Height of Tri. = 6 Hypotenuse = 10 Height of prism = 15 10

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15 Triangular Prism Transfer dimensions to Flattened Figure Step 3: 6 8

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16 Triangular Prism Find the area for each rectangle and triangle Step 4: 8 6 Step 5: Write the area inside the specific shape A = 8 x 15 A = 10 x 15 A = 6 x A = 6 x

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17 Triangular Prism Add all the areas for the total surface area Step 6: =Total surface area

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Try using a table instead of drawing a net. FaceA = ½(bh)Area Triangle½ (8 x 6) 24 Triangle½(8 x 6) 24 Rectangle 1 8 x Rectangle 2 6 x Rectangle 3 10 x Total: 408 sq units

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19 CPS Practice (Fill out a table for this figure as you do each of the next few questions.) What is the area of each of the two triangles? 48 m² 48 m³ 96 m² 96 m³

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20 The three rectangles have the following areas: 150, 150, , 100, , 150, , 180, 150

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21 The total surface area of this triangular prism is: The same as the surface area of the moon.

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22 Cylinder A Cylinder will flatten to a rectangle and two equal circles. Step 1: Flatten the 3-D shape

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23 Cylinder Step 2: Transfer the dimensions to the 3-D shape Height - 15 Diameter - 8 Formulas to use: A = 15 Height Diameter 8 r = d 2 Height 15 r = 4 Diameter = 8 2Π4 = 8Π 25 radius 4 Step 3: Transfer dimensions to the flattened shape 8Π = 25 Length = 15

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24 Cylinder Step 4: Find the area for each shape x 4 x 4 =50 A = 50 A = x 15 Step 5: Add the areas for the shapes = Total surface area

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25 Or, try using a table FaceA =πr2 or A = Ch Area Circleπ4² Circleπ4² Rectangle 8π x Total: sq units Just remember that the circumference of the circle is always one side of the rectangle and the height of the cylinder is the other.

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26 CPS Practice 25 5 What is the approximate area of each of the circles in this cylinder? About 15 sq units About 30 sq units About 100 units About 75 sq units

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How do you find the area of the lateral rectangle for this cylinder? Multiply the circumference of the circle by the height of the cylinder. Multiply the diameter of the circle by the height. Multiply the radius by the height. Multiply any two numbers that you happen to see on the diagram.

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What is the approximate area of the lateral rectangle? 125 sq units About 750 sq units About 75 sq units About 1,200 sq units

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The total surface area is about: 750 sq units 825 sq units 900 sq units The same as a can of Spaghettio’s.

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