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Surface Area of Prisms and Cylinders. Mr. Leshnick. Vocabulary. A net is a pattern you can fold to form a three-dimensional figure. This is a net for a triangular prism. The surface area of a three-dimensional figure is the sum of the areas of its surfaces.
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Surface Area of Prisms and Cylinders Mr. Leshnick
Vocabulary • A net is a pattern you can fold to form a three-dimensional figure. This is a net for a triangular prism.
The surface area of a three-dimensional figure is the sum of the areas of its surfaces. • Find the area of each surface, and add all the areas together.
Example 1 Triangles A = ½ bh A = ½ (26)(18) 8 cm A = ½ (468) 18 cm A = 234 cm2 26 cm 2 Tri’s: 234 x 2 = 468 cm2 Left Rectangle Front and Back Rectangles A = lw A = lw A = (26)(8) A = (18)(8) A = 208 cm2 A = 144 cm2 2 Rect’s: 208 x 2 = 416 cm2
Add up the areas to find surface area. S.A. = 468 cm2 + 144 cm2 + 416 cm2 S.A. = 1,028 cm2
Surface Area of a Cube • A cube has 6 congruent square faces. • Find the area of one face, and multiply it by 6.
Example A = s2 A = 72 A = 49 in2 7 in S.A. = 49(6) S.A. = 294 in2
Surface Area of a Cylinder • A cylinder consists of two circle bases and one rectangular side. • The length of the rectangle is equal to the circumference of the circle. • Find the area of the circles and add it to the area of the rectangle.
Example Rectangle 5 m The width of the rectangle is the height of the cylinder (16 m). The length of the rectangle is the circumference of the circle. 16 m Area of the circles C = 2r C = 2(3.14)(5) A = r2 C = 31.4 m A = 3.14(52) A = lw A = 3.14 (25) A = 31.4(16) A = 78.5 m2 A = 502.4 m2 2 circles: 78.5 x 2 = 157 m2
Put the areas together: S.A. = 157 m2 + 502.4 m2 S.A. = 659.4 m2