Transcript Document
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?