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## 12-3 Surface Areas of Prisms

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**12-3 Surface Areas of Prisms**Kaitlin and Lauren Nelson**Objectives**Find the lateral area of prisms. Find the surface area of prisms.**base**lateral edge altitude lateral faces Parts of a Prism Bases- congruent faces in parallel planes Lateral Faces-the faces that are not bases Lateral Edges-where the lateral faces intersect. Are parallel segments Altitude- Segment that is perpendicular to the bases. Is = height**Types of Prisms**Right Prism-prisms that have lateral edges that are also altitudes. Oblique prism-prism with lateral edges that are not perpendicular to the bases**Lateral Area**The lateral area of a prism, L, is the sum of the areas of the lateral faces. a b c d e f h L = ah+bh+ch+dh+eh+fh L= h(a+b+c+d+e+d+f) L = Ph**EXAMPLE 1!!!!!**Find the lateral area of the regular hexagonal prism, please! 15 cm Lateral area = Perimeter x height 20 cm**WORK IT OUT!**15 cm L= Ph L= [6(15)] 20 L= (90)(20) L= 1800 cm2 20 cm**Surface Area of Prisms**The surface area of a right prism is the lateral area plus the areas of the bases. Surface area = L + 2B**EXAMPLE 2!!!!!**Bartholomew wants to wrap his cheese wedge in tin foil because he forgot his great-uncle’s birthday and wants to make it up to his cheese-loving relative. Find the surface area of the cheese wedge so that Bartholomew knows how much tin foil he will need. SA= L + 2B 6 cm 8 cm 5 cm**WORK IT OUT!**6cm 8 cm 62+ 82= c2 36+ 64= c2 100= c2 10= c L= Ph L= (6+ 8+ 10) 5 L= (24) 5 L= 120 cm2 5 cm 10 cm SA= L+ 2B SA= 120+ 2(24) SA= 120+ 48 SA= 168 cm2 A= ½ (6)(8) A= ½ (48) A= 24 cm2**EXAMPLE 3!!!!!**Pete’s dog, Chalupa con Queso, had an “accident” on his ottoman. If Pete doesn’t reupholster it with his girlfriend’s favorite fabric, she will leave him for a lumberjack with a cat. For Pete’s sake, (ha-ha) figure out the surface area of the ottoman that needs reupholstering. 3 ft 4 ft 2 ft**WORK IT OUT!!**3 ft 4 ft L= Ph L= [2(3)+ 2(4)] 2 L= (6 + 8) 2 L= (14) 2 L= 28 ft2 2 ft A= bh A= (3)(4) A= 12 ft2 SA= L + B SA= 28 + 12 SA= 40 ft2**Dedication**This spiffy-sweet PowerPoint is dedicated to you, you wonderful people…you, for saving Pete’s pride and making Ivan the lumberjack eat flap-jacks with only his cat to keep him company.**Drum roll, please…**Your lovely assignment is…. I hate spelling the word “assignment”. I always get it wrong and I feel like I'm cussing while I type. Oh, my bad. Here you go. Page 651 #6-12,14, 16-21 (Relax people! It’s only fourteen problems. Don’t be hatin’)