Area of a Parallelogram

Date: 01/07/99 at 16:44:39
From: Matthew Colon
Subject: Math

Do you know how to find the area of parallelograms?

Thanks!

Date: 01/08/99 at 08:55:28
From: Doctor Peterson
Subject: Re: Math

Hi, Matthew. Take a deck of cards and look at it on end:

    -----------------------  ---
    -----------------------   ^
    -----------------------   | H
    -----------------------   v
    -----------------------  ---
    |                     |
    |<---------B--------->|

You should know the area of the rectangle you see: B times H, where B 
is the length of the base, and H is the height.

Now slide the deck over so it looks like this:

        -----------------------  ---
       -----------------------    ^
      -----------------------     | H
     -----------------------      v
    -----------------------  -------
    |                     |
    |<---------B--------->|

It still has the same base and the same height, and the area is still 
the same since it's made of the same cards. So the area of a 
parallelogram is the same as the area of a rectangle: B x H. The 
difference is that you have to be very careful about measuring the 
height, since it is not measured along the edge, but is perpendicular 
to the base.

- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/