The height of a cone is 21 cm and its slant height is 28 cm. Find the volume of cone.

We have given that, Height of the cone (h)= 21cm And slant height(l) = 28 cm 

Then, r = $\sqrt{{\mathrm{l}}^2-{\mathrm{h}}^2}$= $\sqrt{{\left(28\right)}^2-{\left(21\right)}^2}=\sqrt{784-441}=\sqrt{343} \mathrm{cm}$

$\Rightarrow {\mathrm{r}}^2=343$

Now, the volume of the cone = $\frac{1}{3}{\mathrm{\pi r}}^2\mathrm{h}= \frac{1}{3}\times \frac{22}{7}\times 343\times 21=22\times 343$

Hence, V = 7546 ${\mathrm{cm}}^3$