# Thread: Finding the are of a Parallelogram with coordinates...? Pre-Calculus

1. ## (Don't read yet) Finding the are of a Parallelogram with coordinates...? Pre-Calculus

Hello. Pre-cal practice work for test tomorrow.

Problem gives us these coordinates: A(1,2), B(5,2), C(3,6), D(5, -3)

I graphed it. How are we supposed to find the area with these coordinates?

I know the answer is 16, because I checked the back of the book. I would like to know how to get that answer.

Thank you

Oh yes, I apologize for the misconveniance.. I will correct this when I get back to my room to access my pre-cal book.

2. ## Re: Finding the are of a Parallelogram with coordinates...? Pre-Calculus

A simple plot of the points shows that this is not a parallelogram...

3. ## Re: Finding the are of a Parallelogram with coordinates...? Pre-Calculus

It is not a parallelogram. Join any diagonal of the quadrilateral. and use the formula for finding the area of a triangle with given vertices.

4. ## Re: Finding the are of a Parallelogram with coordinates...? Pre-Calculus

The problem doesn't make sense.

Problem gives us these coordinates: A(1,2), B(5,2), C(3,6), D(5, -3) .[1]

I graphed it. How are we supposed to find the area with these coordinates?

I know the answer is 16, because I checked the back of the book. .[2]

I would like to know how to get that answer. . So would I!

[1] The vertices are usually labeled in order around the parallelogram.
. . .The given coordinates are not.
. . .Besides, they do not form a parallelogram.
Code:
      |
|     C
|     o
|    *:*
|   * :4*
|  *  :  *
|Ao * * * oB
|   * 4   *
- + - - * - *5 - -
|       * *
|         o
|         D
|
[2] The area is not 16.

Triangle $ABC$ has base 4 and height 4.
. . Its area is $8.$

Triangle $ABD$ has base 4 and height 5.
. . Its area is $10.$

The total area is $18.$

5. ## Re: Finding the are of a Parallelogram with coordinates...? Pre-Calculus

A(1,3) B(5,2) C(3,6) D(7,6)

I know that BXH= Area.
But it's too easy... there must be a trap.
;0