12-3 Surface Areas of Prisms

# 12-3 Surface Areas of Prisms

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## 12-3 Surface Areas of Prisms

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1. 12-3 Surface Areas of Prisms Kaitlin and Lauren Nelson

2. Objectives Find the lateral area of prisms. Find the surface area of prisms.

3. 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

4. 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

5. 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

6. EXAMPLE 1!!!!! Find the lateral area of the regular hexagonal prism, please! 15 cm Lateral area = Perimeter x height 20 cm

7. WORK IT OUT! 15 cm L= Ph L= [6(15)] 20 L= (90)(20) L= 1800 cm2 20 cm

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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.

14. 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’)