Answer:
r = 5.848cm, h = 11.696cm
Step-by-step explanation:
Surface area: ![SA=2\pi rh+2\pi r^2](https://tex.z-dn.net/?f=SA%3D2%5Cpi%20rh%2B2%5Cpi%20r%5E2)
Volume: ![V=\pi r^2h](https://tex.z-dn.net/?f=V%3D%5Cpi%20r%5E2h)
Therefore, the height of a cylinder given its volume would be
, thus:
![SA=2\pi r(\frac{V}{\pi r^2})+2\pi r^2\\\\SA=\frac{2V}{r}+2\pi r^2\\\\SA=\frac{2(400\pi)}{r}+2\pi r^2\\\\SA=\frac{800\pi}{r}+2\pi r^2](https://tex.z-dn.net/?f=SA%3D2%5Cpi%20r%28%5Cfrac%7BV%7D%7B%5Cpi%20r%5E2%7D%29%2B2%5Cpi%20r%5E2%5C%5C%5C%5CSA%3D%5Cfrac%7B2V%7D%7Br%7D%2B2%5Cpi%20r%5E2%5C%5C%5C%5CSA%3D%5Cfrac%7B2%28400%5Cpi%29%7D%7Br%7D%2B2%5Cpi%20r%5E2%5C%5C%5C%5CSA%3D%5Cfrac%7B800%5Cpi%7D%7Br%7D%2B2%5Cpi%20r%5E2)
We now find the derivative of the surface area of the cylinder with respect to its radius and set it equal to 0, solving for the radius:
![\frac{d(SA)}{dr}=-\frac{800\pi}{r^2}+4\pi r](https://tex.z-dn.net/?f=%5Cfrac%7Bd%28SA%29%7D%7Bdr%7D%3D-%5Cfrac%7B800%5Cpi%7D%7Br%5E2%7D%2B4%5Cpi%20r)
![0=-\frac{800}{r^2}+4\pi r](https://tex.z-dn.net/?f=0%3D-%5Cfrac%7B800%7D%7Br%5E2%7D%2B4%5Cpi%20r)
![0=800\pi+4\pi r^3](https://tex.z-dn.net/?f=0%3D800%5Cpi%2B4%5Cpi%20r%5E3)
![-800\pi=4\pi r^3](https://tex.z-dn.net/?f=-800%5Cpi%3D4%5Cpi%20r%5E3)
![-200=r^3](https://tex.z-dn.net/?f=-200%3Dr%5E3)
![r\approx5.848](https://tex.z-dn.net/?f=r%5Capprox5.848)
If
, then the surface area of the cylinder increases
Therefore, the surface area is minimized when the radius is
, making the minimum height
.
In conclusion, the 2nd option is correct.
Hi! Your answer is D explain below!
Answer:
-4
Step-by-step explanation:
Given function
f(x) = -2x² + 3x - 4
Comparing with ax² + bx + c We get
c = - 4
Hope it will help :)❤
Answer:
<em>Diameter Length: ( About ) 5.4 km; Option B</em>
Step-by-step explanation:
~ Let us apply the Area of the Circle formula πr^2, where r ⇒ radius of the circle ~
1. We are given that the area of the circle is 22.9 km^2, so let us substitute that value into the area of the circle formula, solving for r ( radius ) ⇒ 22.9 = π * r^2 ⇒ r^2 = 22.9/π ⇒ r^2 = 7.28929639361.... ⇒
<em>radius = ( About ) 2.7</em>
2. The diameter would thus be 2 times that of the radius by definition, and thus is: 2.7 * 2 ⇒ ( About ) 5.4 km
<em>Diameter Length: ( About ) 5.4 km</em>
It is always B) equals the.