You can easily create and display supplementary angles using GeoGebra. 
     GeoGebra Instruction 1
Graphics     View     under         View     in         Menu.         Line Graphics     View.         You         should         also         get         two         points         on         your         line         named                and         .         Point     on     Object Point Angle 
, and ,
in that order. Repeat for the points
, and .
Move      GeoGebra Instruction 2
Graphics     View     under         View     in         Menu.         Line Graphics     View,         but         be         sure         to         click         the         leftmost         point         first.        You         should         get         a         line         with         two         points         named                and         ,         where                is         the         leftmost         point         of         the         two.         Point Segment Parallel     line Perpendicular     Line Intersect Angle 
, , and ,
in that order. After the angle is drawn, click the points
, , and ,
in that order.
Move