Non-congruent alternate interior angles

This is a house. This object shows non congruent interior angles. The pink line extends down and that forms alternate interior angles that are not congruent with the green line, because one line is obtuse and one angle is acute. In the real world a house is used by people. Houses are found in neighborhoods. This is in the advertisement industry. http://www.google.com/imgres?um=1&hl=en&client=safari&tbo=d&rls=en&biw=1192&bih=639&tbm=isch&tbnid=mmR7VAMB91MUYM:&imgrefurl=http://www.nps.gov/glca/historyculture/navajobridge.htm&docid=kURt39YRODgTsM&imgurl=http://www.nps.gov/glca/historyculture/images/Navajo_Bridges_1.gif&w=556&h=417&ei=_jWgUIa_Da2G0QGxsYHwCw&zoom=1&iact=rc&dur=358&sig=101161591993119626923&page=1&tbnh=146&tbnw=191&start=0&ndsp=18&ved=1t:429,r:6,s:0,i:169&tx=51&ty=63