hey I'm building a shed in my backyard
I'm at the point right now where I'm
building the floor I have the outside
walls what kind of looks like a sandbox
but it's going to support the floor
joist across now before I go any further
I need to make sure that this is an
exact rectangle because if you have it
off of it and it's a parallelogram then
at least all kinds of problems as you
build the building now we've talked
about how to check if something is a
rectangle before those need to be right
angles they all need to be exactly 90
now one way of course you can check it
is using a Pythagorean theorem you could
measure that side you can measure that
side and then you know how long the
diagonal is doing some calculations but
since it's a rectangle there's actually
easier way to do we want it to be a
rectangle now our property of a
rectangle is that the diagonals the two
diagonals that distance to there and
that distance to there should be equal
if it's an exact rectangle those should
be equal so I'm going to measure them
and we'll see if they're not equal then
we know we have some stuff to fix so
we'll measure this one first and here we
have here we have but 189 and a quarter
here see what we have we have a bow just
over one ninety one so those are a
couple inches off from each other so
what that means is this one's longer
than that one so it means even though it
looks like a rectangle it's slightly
like that it's a parallelogram
you
we have to fix that by squaring this off
so I'm going to I'm going to knock these
boards this way and see how we do here
all right let's check that now see what
we're looking at go measure this one
again and we did about an inch there my
guess that is 190 and a quarter roughly
look at that one 19 1/4 so now that
those two diagonals are exactly equal we
know this is an exact rectangle right
angle
you
so there you go using a property of
rectangles to figure out that your
buildings going to be good when you make
it