Answer:
15
Step-by-step explanation:
substitute the values that are given into the expression.
c + a = x
12 + 3 = x
15 = x
I don't see the question . What is the question
Answer:
Volume: ![\frac{2}{3}\pi r^3](https://tex.z-dn.net/?f=%5Cfrac%7B2%7D%7B3%7D%5Cpi%20r%5E3)
Ratio: ![\frac{2}{9}r](https://tex.z-dn.net/?f=%5Cfrac%7B2%7D%7B9%7Dr)
Step-by-step explanation:
First of all, we need to find the volume of the hemispherical tank.
The volume of a sphere is given by:
![V=\frac{4}{3}\pi r^3](https://tex.z-dn.net/?f=V%3D%5Cfrac%7B4%7D%7B3%7D%5Cpi%20r%5E3)
where
r is the radius of the sphere
V is the volume
Here, we have a hemispherical tank: a hemisphere is exactly a sphere cut in a half, so its volume is half that of the sphere:
![V'=\frac{V}{2}=\frac{\frac{4}{3}\pi r^3}{2}=\frac{2}{3}\pi r^3](https://tex.z-dn.net/?f=V%27%3D%5Cfrac%7BV%7D%7B2%7D%3D%5Cfrac%7B%5Cfrac%7B4%7D%7B3%7D%5Cpi%20r%5E3%7D%7B2%7D%3D%5Cfrac%7B2%7D%7B3%7D%5Cpi%20r%5E3)
Now we want to find the ratio between the volume of the hemisphere and its surface area.
The surface area of a sphere is
![A=4 \pi r^2](https://tex.z-dn.net/?f=A%3D4%20%5Cpi%20r%5E2)
For a hemisphere, the area of the curved part of the surface is therefore half of this value, so
. Moreover, we have to add the surface of the base, which is
. So the total surface area of the hemispherical tank is
![A'=2\pi r^2 + \pi r^2 = 3 \pi r^2](https://tex.z-dn.net/?f=A%27%3D2%5Cpi%20r%5E2%20%2B%20%5Cpi%20r%5E2%20%3D%203%20%5Cpi%20r%5E2)
Therefore, the ratio betwen the volume and the surface area of the hemisphere is
![\frac{V'}{A'}=\frac{\frac{2}{3}\pi r^3}{3\pi r^2}=\frac{2}{9}r](https://tex.z-dn.net/?f=%5Cfrac%7BV%27%7D%7BA%27%7D%3D%5Cfrac%7B%5Cfrac%7B2%7D%7B3%7D%5Cpi%20r%5E3%7D%7B3%5Cpi%20r%5E2%7D%3D%5Cfrac%7B2%7D%7B9%7Dr)
Hello,
No a triangle with these angles are not unique. This is because every triangle is supposed to have 180 degrees, just like this one.
Have a great day!