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Answer:
Volume of regular pentagonal prism = 1.72 cm³ (Approx.)
Step-by-step explanation:
Given:
Side of regular pentagonal prism = 1 cm
Height of regular pentagonal prism = 1 cm
Find:
Volume of regular pentagonal prism
Computtaion:
Volume of regular pentagonal prism = (1/4)[√5(5+2√5)]a²h
Volume of regular pentagonal prism = (1/4)[√5(5+2√5)](1)²(1)
Volume of regular pentagonal prism = (1/4)[√5(5+2√5)]
Volume of regular pentagonal prism = (0.25)[√5{5+4.472}]
Volume of regular pentagonal prism = (0.25)[√5{9.472}]
Volume of regular pentagonal prism = (0.25)[√47.36]
Volume of regular pentagonal prism = (0.25)[6.8818]
Volume of regular pentagonal prism = 1.72045
Volume of regular pentagonal prism = 1.72 cm³ (Approx.)
Answer:
217.96 or 218.0 in Big Ideas Math
Step-by-step explanation:
volume of the whole prism - smaller inner prism
Bigger Prism (apothem = 4, height = 6)
360/5 = 72 72/2 = 36
4 · tan (36) = 2.906
2.906 · 4 = 11.6247
11.6247 · 5 = 58.1234 ← The area of the Pentagon
58 · 6 = 348.740 ← The Bigger Prism Volume
Smaller Prism (apothem = 3, height = 4)
Keep in mind that the bottom, sides, and top of the box is one centemeters thick ⇒ smaller pentagon ⇒ (apothem = 4-1, height = 6 - 2)
3 · tan (36) = 2.1796
2.1796 · 3 = 6.5389
6.5389 · 5 = 32.6944 ← small Pentagon Area
32.6944 · 4 = 130.7777 ← Small Pentagon Prism Volume
Final Step
Area of big prism - small prism
348.74041 - 130.7777 = 217.9627
Round to the nearest tenth ⇒ 218.0