Both lines in the image above are lines on to different planes, the lines are not parallel and are not vertical angles.
These lines are skew lines.
Construction worker create skew lines many times in a building.
http://www.google.com/imgres?q=building&um=1&hl=en&safe=active&tbo=d&biw=1280&bih=894&tbm=isch&tbnid=O08cY0IaTDMoBM:&imgrefurl=http://www.toledoblade.com/local/2012/10/08/Historic-downtown-building-falling-apart-fromneglect.html&docid=fOBRe2sJEBlXiM&imgurl=http://www.toledoblade.com/image/2012/10/08/800x_b1_cCM_z/The-historic-Nicholas-Building-downtown-has-fallen-into-serious-disrepair.jpg&w=800&h=1200&ei=RniUJn3Aq80QGYsICoDQ&zoom=1&iact=hc&vpx=221&vpy=149&dur=423&hovh=246&hovw=165&tx=87&ty=135&sig=112621608789265777111&page=2&tbnh=164&tbnw=114&start=42&ndsp=51&ved=1t:429,r:32,s:20,i:229
