Answer:
The volume of pyramid B is 81 cubic units
Step-by-step explanation:
Given
<u>Pyramid A</u>
-- base sides
-- Volume
<u>Pyramid B</u>
--- base sides
Required
Determine the volume of pyramid B <em>[Missing from the question]</em>
From the question, we understand that both pyramids are equilateral triangular pyramids.
The volume is calculated as:
![V = \frac{1}{3} * B * h](https://tex.z-dn.net/?f=V%20%3D%20%5Cfrac%7B1%7D%7B3%7D%20%2A%20B%20%2A%20h)
Where B represents the area of the base equilateral triangle, and it is calculated as:
![B = \frac{1}{2} * s^2 * sin(60)](https://tex.z-dn.net/?f=B%20%3D%20%5Cfrac%7B1%7D%7B2%7D%20%2A%20s%5E2%20%2A%20sin%2860%29)
Where s represents the side lengths
First, we calculate the height of pyramid A
For Pyramid A, the base area is:
![B = \frac{1}{2} * s^2 * sin(60)](https://tex.z-dn.net/?f=B%20%3D%20%5Cfrac%7B1%7D%7B2%7D%20%2A%20s%5E2%20%2A%20sin%2860%29)
![B = \frac{1}{2} * 4^2 * \frac{\sqrt 3}{2}](https://tex.z-dn.net/?f=B%20%3D%20%5Cfrac%7B1%7D%7B2%7D%20%2A%204%5E2%20%2A%20%5Cfrac%7B%5Csqrt%203%7D%7B2%7D)
![B = \frac{1}{2} * 16 * \frac{\sqrt 3}{2}](https://tex.z-dn.net/?f=B%20%3D%20%5Cfrac%7B1%7D%7B2%7D%20%2A%2016%20%2A%20%5Cfrac%7B%5Csqrt%203%7D%7B2%7D)
![B = 4\sqrt 3](https://tex.z-dn.net/?f=B%20%3D%204%5Csqrt%203)
The height is calculated from:
![V = \frac{1}{3} * B * h](https://tex.z-dn.net/?f=V%20%3D%20%5Cfrac%7B1%7D%7B3%7D%20%2A%20B%20%2A%20h)
This gives:
![36 = \frac{1}{3} * 4\sqrt 3 * h](https://tex.z-dn.net/?f=36%20%3D%20%5Cfrac%7B1%7D%7B3%7D%20%2A%204%5Csqrt%203%20%2A%20h)
Make h the subject
![h = \frac{3 * 36}{4\sqrt 3}](https://tex.z-dn.net/?f=h%20%3D%20%5Cfrac%7B3%20%2A%2036%7D%7B4%5Csqrt%203%7D)
![h = \frac{3 * 9}{\sqrt 3}](https://tex.z-dn.net/?f=h%20%3D%20%5Cfrac%7B3%20%2A%209%7D%7B%5Csqrt%203%7D)
![h = \frac{27}{\sqrt 3}](https://tex.z-dn.net/?f=h%20%3D%20%5Cfrac%7B27%7D%7B%5Csqrt%203%7D)
To calculate the volume of pyramid B, we make use of:
![V = \frac{1}{3} * B * h](https://tex.z-dn.net/?f=V%20%3D%20%5Cfrac%7B1%7D%7B3%7D%20%2A%20B%20%2A%20h)
Since the heights of both pyramids are the same, we can make use of:
![h = \frac{27}{\sqrt 3}](https://tex.z-dn.net/?f=h%20%3D%20%5Cfrac%7B27%7D%7B%5Csqrt%203%7D)
The base area B, is then calculated as:
![B = \frac{1}{2} * s^2 * sin(60)](https://tex.z-dn.net/?f=B%20%3D%20%5Cfrac%7B1%7D%7B2%7D%20%2A%20s%5E2%20%2A%20sin%2860%29)
Where
![s = 6](https://tex.z-dn.net/?f=s%20%3D%206)
So:
![B = \frac{1}{2} * 6^2 * sin(60)](https://tex.z-dn.net/?f=B%20%3D%20%5Cfrac%7B1%7D%7B2%7D%20%2A%206%5E2%20%2A%20sin%2860%29)
![B = \frac{1}{2} * 36 * \frac{\sqrt 3}{2}](https://tex.z-dn.net/?f=B%20%3D%20%5Cfrac%7B1%7D%7B2%7D%20%2A%2036%20%2A%20%5Cfrac%7B%5Csqrt%203%7D%7B2%7D)
![B = 9\sqrt 3](https://tex.z-dn.net/?f=B%20%3D%209%5Csqrt%203)
So:
![V = \frac{1}{3} * B * h](https://tex.z-dn.net/?f=V%20%3D%20%5Cfrac%7B1%7D%7B3%7D%20%2A%20B%20%2A%20h)
Where
and ![h = \frac{27}{\sqrt 3}](https://tex.z-dn.net/?f=h%20%3D%20%5Cfrac%7B27%7D%7B%5Csqrt%203%7D)
![V = \frac{1}{3} * 9\sqrt 3 * \frac{27}{\sqrt 3}](https://tex.z-dn.net/?f=V%20%3D%20%5Cfrac%7B1%7D%7B3%7D%20%2A%209%5Csqrt%203%20%2A%20%5Cfrac%7B27%7D%7B%5Csqrt%203%7D)
![V = \frac{1}{3} * 9 * 27](https://tex.z-dn.net/?f=V%20%3D%20%5Cfrac%7B1%7D%7B3%7D%20%2A%209%20%2A%2027)
![V = 81](https://tex.z-dn.net/?f=V%20%3D%2081)