It'd be great if someone could help me on this!
A family is building an underground tornado shelter. To fit the whole family they need the floor to have an area of 20 square feet and the high should be at least 7.2 feet. What volume will the shelter occupy?

 144 square feet

Step-by-step explanation:

volume = length x width x height

volume = area x height

v = 20 x 7.2 = 144

the answer is b

geometry: triangles

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call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584