What's the common ray? (1-4)
On the screen, we can see two angles AOB and BOC. We can change the value of angles AOB and BOC using their respective slide bars. Let us change the values of angles and observe how their shape gets changed.
Think what name we can give to this pair of angles?
Are adjacent angles always congruent?
COB and AOB have a shared ray. Name that ray. (use the fancy "insert math" button to find the angle symbol, located in the miscellaneous tab)