Presentation on theme: "Bell Work Find the surface area of each figure."— Presentation transcript:
1 Bell Work Find the surface area of each figure. 13 x 23 = 299 cm²10 x 23 = 230 cm²( ½ )(10)(12) = 60 cm²Add them up!SA =SA = 948 cm²6 x 4 = 24 in²3 x 4 = 12 in²6 x 3= 18 in²Add them up!SA =SA = 108 in²
3 DefinitionSurface Area – is the total number of square units used to cover a 3-D surface.
4 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 is area!
5 Shortcut for surface Area You can find the SA of any prism by using the basic formula for SA which is:SA= 2B + PhPh = The surface area of all of the sides.The sum of the surface areas of all of the faces excluding the bases.To find Ph: perimeter of the base x height of the prism.B = the area of the base of the prism.
6 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 + PhEither method will give you the same answer.
8 3. The back rectangle is different Find the AREA of each SURFACE1. Top and bottom triangle:A = 2(½ bh)A =2( ½ )(6)(6)A = 362. The two sides are the same.A = 2lwA = 2(6)(9)A = 108Example:8mm9mm6 mm mm3. The back rectangle is differentA = lwA = 8(9)A = 724. ADD THEM ALL UP!SA = 216 mm²SA= 2B + PhSA= 2(18) + 20(9)SA=SA = 216 mm²B = ( ½ )(6)(6) = 18P = = 20h = 9OR
9 Cube Are all the faces the same? YES How many faces are there? 6 4m Find the Surface area of one of the faces.4 x 4 = 16Take that times the number of faces.X 696 m2SA for a cube.
10 Example Find the Surface Area SA= 2B + Ph SA= 2(16) + 20(15) SA= 332 in²B = 2 x 8 = 16 in²P = = 20 in
11 Example Find the Surface Area SA= 2B + Ph SA= 2(184) + 50.4(21.5) SA= 1,451.6 cm²Perimeter of Base = (8.4)(6)P= 50.4 cm
12 Example Find the Surface Area CUBE Area of one face: 5² = 25 SA= (6)(25)SA= 150 m²
13 ExampleThe area of one base of a triangular prism is 18 square feet. The perimeter of the triangular base is 19 feet. The height of the prism is 21 feet. Find the surface area of the triangular prism.SA= 2B + PhSA= 2(18) + 19(21)SA =SA= 435 ft²21 ft
14 ExampleHow much wrapping paper do you need to completely cover a rectangular box that is 20 inches by 18 inches by 6 inches?SA= 2B + PhSA= 2(360) + 76(6)SA=SA= 1176 in²B = 20 x 18 = 360 in²P = = 76 in
15 Practice: Surface Area Worksheet REMEMBER. When in doubt… Practice: Surface Area Worksheet REMEMBER! When in doubt….draw a net to find the surface area!