Vertex (of an angle)
Definition

The vertex of an angle is the common endpoint of two rays that form the angle.

Vertex of an angle

Real World Examples
http://www.clipart.com_Filename:23269311.jpg http://www.clipart.com_Filename:15870527.jpg http://www.clipart.com_Filename:040501_1952_2470_a__s.thb.jpg

Demonstration
Image only

Instructions text as in global.js

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