Approximate the change in the volume of a night circular cylinder of foxed radius \( \mathrm{r}=21 \mathrm{~cm} \) when its height decreases from \( \mathrm{h}=12 \mathrm{~cm} \) to \( \mathrm{h}=11.9 \mathrm{~cm}\left(\mathrm{~V}(\mathrm{~h})=\pi^{2} \mathrm{~h}\right) \). Use a linear approximation.
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To approximate the change in volume, we'll use the formula for the volume of a cylinder, \( V(h) = \pi r^2 h \). Since the radius is fixed at \( r = 21 \, \text{cm} \), the volume can be simplified to \( V(h) = \pi (21)^2 h = 441\pi h \). Now, we want to find how the volume changes when height \( h \) decreases from \( 12 \, \text{cm} \) to \( 11.9 \, \text{cm} \). The derivative of the volume with respect to height is: \[ \frac{dV}{dh} = 441\pi. \] Using linear approximation, the change in volume \( dV \) when \( h \) changes by \( dh = -0.1 \, \text{cm} \) is given by: \[ dV \approx \frac{dV}{dh} \cdot dh = 441\pi \cdot (-0.1) = -44.1\pi \, \text{cm}^3. \] Therefore, the approximate change in volume as the height decreases from \( 12 \, \text{cm} \) to \( 11.9 \, \text{cm} \) is about \( -44.1\pi \, \text{cm}^3 \).