polygon
![](https://i.ytimg.com/vi/_XO8tJJuFhE/mqdefault.jpg)
3:52
angles of elevation and depression
![](https://i.ytimg.com/vi/quGb7u5N3cM/mqdefault.jpg)
2:36
circle theorems
![](https://i.ytimg.com/vi/giRvglUxYUY/mqdefault.jpg)
9:36
Metra BNSF railfanning both rush hours at Naperville and exploring Aurora, IL
![](https://i.ytimg.com/vi/L3SZ4gLhzDo/mqdefault.jpg)
10:52
A Nice Algebra Problem | Math Olympiad | Solve for x values?
![](https://i.ytimg.com/vi/WzfFCRAQV-s/mqdefault.jpg)
3:03
CYCLIC QUADRILATERAL
![](https://i.ytimg.com/vi/4I6hShFlFAU/mqdefault.jpg)
6:10
NS 8154 leads a Monstrous 18D in Union, SC
![](https://i.ytimg.com/vi/3lJZPonJSuY/mqdefault.jpg)
5:43
Tráfico de las obras ferroviarias de Workington
![](https://i.ytimg.com/vi/p5yQQp1RQFk/mqdefault.jpg)
7:14