Q:

The right pengtagonal prism has a height of of 14 units. The volume of the prism is 840 cubic units. What is the perimeter of the base? 12 units 15 units 21 units 30 units

Accepted Solution

A:
Answer:Option D is correct.Step-by-step explanation:Height of prism = 14 unitsVolume of prism = 840 cubic unitsPerimeter of base = ?Volume of Prism = Base Area * Height840 = Base Area * 14=>Base Area = 840/ 14Base Area = 60 square unit.Now Area of pentagon:[tex]Area=\frac{a^2}{4}\sqrt{5(5+2\sqrt{5}}[/tex]We need to find a, where Area = 60[tex]60=\frac{a^2}{4}*6.88\\60=a^2*1.72\\=>a^2=60/1.72\\=>a^2=34.88\\=>a=\sqrt{34.88}\\ a=5.91[/tex]The pentagon has 5 sides.So, perimeter of base = 5*aperimeter of base = 5* 5.91perimeter of base = 29.55 β‰ˆ 30 unitsSo, Option D is correct.