100 likes | 146 Views
3D Figures, Surface Area and Nets. 3D Figures. What is a 3D figure? A solid shape with length, width, and height rectangular prisms cube cone cylinder pyramid. 3D Figures. Most 3D figures have Faces – the flat surfaces or sides
E N D
3D Figures • What is a 3D figure? • A solid shape with length, width, and height rectangular prisms cube cone cylinder pyramid
3D Figures • Most 3D figures have • Faces – the flat surfaces or sides • Edges – where the faces meet each other • Vertices – points where the edges meet or the “corners”
3D Figures • Let’s look at a cube. How many….. • Faces? • Edges? • Vertices? 6 12 8
Surface Area • Surface area – the total area of the OUTSIDE of an object • Example – Think of how much wrapping paper you would need to wrap a box. • How do I find surface area? • find the area of all the faces and add them together
Nets • What is a net? • A net is the pattern made when a 3D figure is laid out flat showing each face of the figure. A net is folded to make a 3D figure.
Nets and Surface Area • You can use nets to help you find the surface area of a 3D figure. • If you take the net of a cube, you see all the faces are squares. You can find the area of 1 of the faces and multiply it by 6 to find the surface area of the entire cube. • Area of a square? s • Cube: SA=s*s*6 or s²*6 • s=3
Rectangular Prism • Find the area of each face and add them all together. All of the faces are rectangles. How many faces? • Top and bottom faces are the same, the front and back faces are the same, and the left and right faces are the same SA= (lw + lw) + (hl + hl) + (hw + hw) • l=8 • w=3 • h=4 SA = (8 x 3 + 8 x 3) + (4 x 8 +4 x 8) + (4 x 3 + 4 x 3) SA = ( 24 + 24 ) + ( 32 + 32 ) + ( 12 + 12) SA = 48 + 64 + 24 Surface Area = 136 cm2
Pyramid 4 Triangles 1 Square • What shapes make up the faces of a pyramid? • Find the area of the base and the area of the 4 sides. Add them together. • Base Area= s*s • Side Area= (1/2)b*h • s = 2 • b=2 • h=3