A structure which has a square base and four triangular sides meeting at a point is called pyramid.
At distance of 3.97 feet from its vertex , pyramid is cut by plane so that the two solids of equal weight will be formed.
<u>It is assumed that weight of pyramid is proportional to its volume.</u>
So,
, where V is volume of original pyramid and v is volume of small pyramid and k is constant.
Let us consider that at h distance, pyramid is cut from its vertex. So a small pyramid is also formed.
Assume that base area of original pyramid is A and base of small pyramid is a.
Volume of original pyramid is, ![V= \frac{1}{3} *A* 5](https://tex.z-dn.net/?f=V%3D%20%5Cfrac%7B1%7D%7B3%7D%20%20%2AA%2A%205)
So, weight of original pyramid, ![W = k *(\frac{1}{3} *A* 5) = 800](https://tex.z-dn.net/?f=W%20%3D%20k%20%2A%28%5Cfrac%7B1%7D%7B3%7D%20%20%2AA%2A%205%29%20%3D%20800)
Volume of small pyramid is, ![v = \frac{1}{3}* a* h](https://tex.z-dn.net/?f=v%20%3D%20%5Cfrac%7B1%7D%7B3%7D%2A%20a%2A%20h)
So, weight of small pyramid, ![w = k*(\frac{1}{3}* a* h)=400](https://tex.z-dn.net/?f=w%20%3D%20k%2A%28%5Cfrac%7B1%7D%7B3%7D%2A%20a%2A%20h%29%3D400)
<u>Since, base and height of small pyramid and original pyramid are in proportion.</u>
So, ![\frac{a}{A} = (\frac{h}{5}) ^{2}](https://tex.z-dn.net/?f=%5Cfrac%7Ba%7D%7BA%7D%20%20%3D%20%28%5Cfrac%7Bh%7D%7B5%7D%29%20%5E%7B2%7D)
![a = (\frac{h}{5} )^{2}A](https://tex.z-dn.net/?f=a%20%3D%20%28%5Cfrac%7Bh%7D%7B5%7D%20%29%5E%7B2%7DA)
Substituting value of a in equation ![k*(\frac{1}{3}* a* h)=400](https://tex.z-dn.net/?f=k%2A%28%5Cfrac%7B1%7D%7B3%7D%2A%20a%2A%20h%29%3D400)
So, ![k*(\frac{1}{3}* \frac{h^{2} }{25}A * h)=400](https://tex.z-dn.net/?f=k%2A%28%5Cfrac%7B1%7D%7B3%7D%2A%20%5Cfrac%7Bh%5E%7B2%7D%20%7D%7B25%7DA%20%2A%20h%29%3D400)
![(k*\frac{1}{3}* A*5)*\frac{1}{5} *\frac{h^{2} }{25} * h)=400](https://tex.z-dn.net/?f=%28k%2A%5Cfrac%7B1%7D%7B3%7D%2A%20A%2A5%29%2A%5Cfrac%7B1%7D%7B5%7D%20%2A%5Cfrac%7Bh%5E%7B2%7D%20%7D%7B25%7D%20%2A%20h%29%3D400)
Since,
, substitute in above equation.
So, ![800*\frac{h^{3} }{125}=400\\\\h^{3}=\frac{125}{2}\\\\h=\sqrt[\frac{1}{3} ]{62.5}\\\\h=3.97 feet](https://tex.z-dn.net/?f=800%2A%5Cfrac%7Bh%5E%7B3%7D%20%7D%7B125%7D%3D400%5C%5C%5C%5Ch%5E%7B3%7D%3D%5Cfrac%7B125%7D%7B2%7D%5C%5C%5C%5Ch%3D%5Csqrt%5B%5Cfrac%7B1%7D%7B3%7D%20%5D%7B62.5%7D%5C%5C%5C%5Ch%3D3.97%20feet)
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brainly.com/question/17950304