Just do those things and simplify:
![image](https://i0.wp.com/66.media.tumblr.com/10f24dd2fb5db5556ddc92d1c4a10366/tumblr_inline_phfyu9767s1qio24w_540.png?w=852&ssl=1)
![image](https://i0.wp.com/66.media.tumblr.com/2b17ab5508783245792184276f1103f3/tumblr_inline_phfyzzz0No1qio24w_540.png?w=852&ssl=1)
Looks like the volume of the second cylinder is half the volume of the first! 🙂
The shortcut here is to recognize that the r value gets squared but the h value doesn’t, so you can say the volume is divided by 4 then multiplied by 2.
from Tumblr https://ift.tt/2De8uzO