Chapter7C.1. Surface area Michael Liu Grade 9 Definition：surface area ?A plane face is one which is flat. ?This means that the surface area is the same as the area of the net required to m
ake the Definition：surface area ?What does it mean to you? ?The surface area of a threedimensional solid with plane faces is the sum of the areas of the faces. Example : Triangular prism ? The surface area of the following triangular prism. B'' B' B' A'' B C' The SA is same as the area of : Area of side 1 Area of side 2 Area of side 3 Vocabulary A rectangular prism always has 6 faces, or sides. ____ Top Back Side 2 Front Bottom Side 1 Height (H) Width (W) Length (L) 5 More About Faces wait.. 1 Vocabulary To help us see all six faces of a rectangular prism, mathematicians sometimes unfold the rectangular prism to see a drawing called a net. Top Side Side Front Side Top Front Bottom You can easily see all three pairs of faces in a net. Internet applet: 7 Back Net of a cube wait.. 1 Practice – Independent Example So, how do we find the surface area of this rectangular prism? Let’s try an example… Front Back Side 1 Side 2 Top Bottom Take a couple minutes to see how many faces you can find the area of. If you can, also try to find the total surface area. 3 cm 4 cm 2 cm 8 Scaffolding Practice – Guided Example Surface area of the rectangular prism Side 2 Top Side Front Side Remember: Bottom Back Back Front = 4 cm x 3 cm = 12 cm2 = 12 cm2 = 6 cm2 = 6 cm2 = 8