---
cards-deck: default_obsidian
---

#math/calculus 

# cutoff of cone
taken via an integral of the circumference times length of side of the cone. It's weird, because the cones vs cylinders derivation is pretty unnecessary. It becomes sort of the same thing. 

## formula
#card/reverse 
$\pi l_{2}(r_{1}+r_{2})=2\pi l_{2}\bar{r}$ (2X the average r)
Good for measuring the surface area of a line's rotation round an axis.
$L_2$ being the length of the line we're measuring over.
^1652711080597