



Take a
square and stretch it in one direction.












You
get a rectangle. 





The
angles are still 90 degrees. 


Sides
across from each other are still the same size. 


Sides
across from each other are still parallel. 





We
could use a bunch of the games from back in 


"two
lines crossed by another line" 


to
show that the sides across from each other 


are
really parallel. 











Back
then, we had a rule that said 


"If
two lines are crossed by another line, 


and
the same side interior angles add up to 180 degrees 


then
the lines are parallel" 





So
when you have a rectangle, 


the
sides across from each other really are parallel. 





Wonderful. 





Diagonal
lines inside a rectangle don't work exactly the same way 


as
they do in a square. 


Some
things do work the same way, 


some
things don't. 











THINGS
THAT DO WORK THE SAME WAY: 



1) The
two diagonal lines are both the same length 



2) The
two diagonal lines cur each other exactly in half 



3) Each
diagonal line creates right triangles with two of the rectangle
sides 





THINGS
THAT DON'T WORK THE SAME WAY 



1)The
angles we get where the diagonal lines cross are NOT 90 degrees 



2) The
diagonal lines DO NOT cut the angles 



at the corners of the
rectangles exactly in half. 





copyright 2005 Bruce Kirkpatrick 
