Source: mnhnmath at YouTube: https://www.youtube.com/watch?v=jDdwdzyuNB4
Source: patrickJMT at YouTube: https://www.youtube.com/watch?v=-vwcLvb9A0s
Vertical Asymptote Example
Source: integralCALC at YouTube: http://www.youtube.com/watch?v=D2gA9bP3rKA
Trigonometric Function Example
Source: integralCALC at Youtube: http://www.youtube.com/watch?v=7dpsjhFZiGA
Source: johnbrykmath at YouTube: http://www.youtube.com/watch?v=55K3XBBb4pI
Source: atcmathprof at YouTube: http://www.youtube.com/watch?v=GlE3eSZpO9c
Source: ProfRobBob at YouTube: https://www.youtube.com/watch?v=C-4MKM4KXvg