In geometry, the angle symbol is used to denote an angle formed by three points. The middle point corresponds to the vertex at which the angle lies. Typically the angle symbol is used in an expression like this:
$∠ABC$
In plain language this means the angle is formed by the three points A, B, and C with the vertex at point B. Below are various text and image formats for the angle symbol.
Symbol  Format  Data 

∠  Unicode 

$∠$  TeX 

SVG 