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Even though a cylinder is a 3D solid, you can still measure lengths on a 2D cross-section.
How do you calculate a difference?
Use variables.
Example Solution:
Example Solution:
| Radius | Height | Volume |
|---|---|---|
| 1in. | 3in. | π* 1^2*3 = 3πin.^3 |
| 1.5in. | 2in. | π* 1.5^2*2 = 4.5πin.^3 |
The difference can be found by subtracting the volume of the smaller cylinder from the volume of the larger cylinder.
Example Solution: V_L-V_S=1.5Ï€
The table below summarizes the measurements.
| Radius | Height |
|---|---|
| 1in. | 3in. |
| 1.5in. | 2in. |
Let's use the formula to find the volume of the cylinder on the left.
r= 1, h= 3
Calculate power and product
Multiply
We can find the volume of the other cylinder similarly. Let's include a column in the table for the volumes.
| Radius | Height | Volume |
|---|---|---|
| 1in. | 3in. | π* 1^2*3 = 3πin.^3 |
| 1.5in. | 2in. | π* 1.5^2*2 = 4.5πin.^3 |
The difference can be found by subtracting the volume of the smaller cylinder from the volume of the larger cylinder.
If we call the volume of the smaller cylinder V_S and the volume of the larger cylinder V_L, then we can use subtraction to express the difference.
V_L= 4.5Ï€, V_S= 3Ï€
Factor out π
Subtract term
The difference of the volumes of the cylinders sketched in Part A is 1.5Ï€ cubic inches.