GEOMETRY HELP Use a net to find the surface area of the cube. Draw a net for the cube. Find the area of one face.11 2 = 121 The area of each face is 121 in. 2. Surface Area = sum of areas of lateral faces + area of bases = ( ) + ( ) = = 726 Because there are six identical faces, the surface area is 726 in. 2. Quick Check Surface Areas of Prisms and Cylinders LESSON 11-2 Additional Examples

GEOMETRY HELP Find the surface area of a 10-cm high right prism with triangular bases having 18-cm edges. Round to the nearest whole number. Use the formula L.A. = ph to find the lateral area and the formula S.A. = L.A. + 2B to find the surface area of the prism. The area B of the base is ap, where a is the apothem and p is the perimeter Draw the base. Use 30°-60°-90° triangles to find the apothem. The triangle has sides of length 18 cm, so p = 3 18 cm, or 54 cm. Surface Areas of Prisms and Cylinders LESSON 11-2 Additional Examples

GEOMETRY HELP The area of each base of the prism is 81 3 cm 2. (continued) S.A. = L.A. + 2BUse the formula for surface area. = ph + 2B Rounded to the nearest whole number, the surface area is 821 cm B = ap =  3 3  54 = a =  = = 3 3 Rationalize the denominator. Surface Areas of Prisms and Cylinders LESSON 11-2 Additional Examples Quick Check = Use a calculator. 9 = 3  alonger leg  3  shorter leg 2(81 3 )Substitute = (54)(10) +

GEOMETRY HELP S.A. = L.A. + 2BUse the formula for surface area of a cylinder. = 2 (6)(9) + 2 (6 2 )Substitute 6 for r and 9 for h. The surface area of the cylinder is 180 ft 2. Quick Check = 2 rh + Substitute the formula for lateral area of a cylinder and area of a circle. 2( r 2 ) = Simplify. = Surface Areas of Prisms and Cylinders LESSON 11-2 Additional Examples The radius of the base of a cylinder is 6 ft, and its height is 9 ft. Find its surface area in terms of.

GEOMETRY HELP A company sells cornmeal and barley in cylindrical containers. The diameter of the base of the 6-in. high cornmeal container is 4 in. The diameter of the base of the 4-in. high barley container is 6 in. Which container has the greater surface area? Find the surface area of each container. Remember that r =. d2d2 S.A. = L.A. + 2B Cornmeal ContainerBarley Container Use the formula for surface area of a cylinder. = 2 rh + 2 r 2 Substitute the formulas for lateral area of a cylinder and area of a circle. Surface Areas of Prisms and Cylinders LESSON 11-2 Additional Examples

GEOMETRY HELP Cornmeal Container Barley Container = 32 = 42 Because 42 in. 2  32 in. 2, the barley container has the greater surface area. (continued) = (2)(6) + (2 2 ) = (3)(4) + (3 2 ) Substitute for r and h = 24 + Simplify. 818 Surface Areas of Prisms and Cylinders LESSON 11-2 Additional Examples Quick Check