In order to find the measure of the side that is missing we look at the sides of the figure that are parallel to the one missing in this case, the 12cm and 4cm sides.
then if we maintain the proportion of both sides and knowing that they must be parallel between each other in order to meet at right angleswe can say that the missing side is difference between both sides:
[tex]12-4=8cm[/tex]
the missing sideis 8 cm.
