Answer:
8 inch³
Step-by-step explanation:
Side should be 2 inch
Volume = side³ = 2³ = 8 inch³
So Volume of cylinder is pi*r^2*h = 1,000
Then lightest one means you have the smallest surface area. Which is one base and then the area of the surface. SA = pi*r^2 + 2pi*r*h
So now you have 2 equations, so:
h = 1,000/(pi*r^2)
So then SA = pi*r^2 + 2pi*r*(1,000/(pi*r^2) = pi*r^2 + 2,000/r
Derivative of SA is then 2pi*r -2,000/r^2. Set to 0
2pi*r-2,000/r^2 =0 --> 2pi*r^3 = 2,000 --> r^3 = 1,000/pi --> r = 10/pi^(1/3)
Now go back to the volume function: pi*r^2*h =1,000 --> 1,000/(pi*100/pi^(2/3)) = h
<span>h = 10 / pi^(1/3)</span>
ANSWER
![-\frac{\sqrt[]{3}}{2}](https://tex.z-dn.net/?f=-%5Cfrac%7B%5Csqrt%5B%5D%7B3%7D%7D%7B2%7D)
EXPLANATION
Given
We can find cos 150 by using
recall that
![\begin{gathered} \cos 30=\frac{\sqrt[]{3}}{2} \\ \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20%5Ccos%2030%3D%5Cfrac%7B%5Csqrt%5B%5D%7B3%7D%7D%7B2%7D%20%5C%5C%20%20%5Cend%7Bgathered%7D)
Hence,
![\begin{gathered} \cos 150=-\cos 30 \\ =-\frac{\sqrt[]{3}}{2} \\ \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20%5Ccos%20150%3D-%5Ccos%2030%20%5C%5C%20%3D-%5Cfrac%7B%5Csqrt%5B%5D%7B3%7D%7D%7B2%7D%20%5C%5C%20%20%5Cend%7Bgathered%7D)
Therefore, the value of cos 150 is
