Presentation on theme: "1.3 Surface Areas of Objects Made from Right Rectangular Prisms"— Presentation transcript:
11.3 Surface Areas of Objects Made from Right Rectangular Prisms
2Determining the SA of a Composite Object Made From Cubes Each cube has edge length of 2cm. Determine the surface area.
3Method 1Draw all 6 views and count all the squares.FrontLeft SideTop432BottomRight Side3Back24Total: 18 Squares
4The area of each square is: A= l x wA= 2cm x 2cm = 4 cm2We have 18 of these squares, so:Total Area = 18 x 4 cm2 = 72 cm2
5Method 2Our composite object is made up of 4 squares. Each cube has 6 square faces. So the total number of squares is: 4 x 6 = 18
6The cubes overlap at 3 places, so there are 3x2, or 6 squares that are not included in the surface area.So the surface area in squares is: 24 – 6 = 18Each square has area 2cm x 2cm = 4cm2So the surface area is 18 x 4cm2 = 72cm2
7Determining the Surface Area of a Composite Object Made from Right Rectangular Prisms
82 1 3 1 2 3 50 m 30 m 30 m 20 m 20 m 30 m 20 m 6 Squares, each have side length 10m
9My favourite method: Figure out the Surface area of all the objects. Figure out the surface area where the objects overlap.Subtract that area from the total.