Geometry

$angle:~draw~the~2~endpoints~to~the ~center ~and~ find ~that~ angle \\ length:~360/[angle]*[circumfrence]\\ area:~360/[angle]*[area ~of ~circle]$

or

angle: draw the 2 endpoints to the center and find that angle 

length: 360/[angle]*[circumfrence]

area: 360/[angle]*[area of circle]