4 Answers

Start by drawing the area(S) on graph paper, using the measurements you obtained. Make sure your drawing is to scale. For instance, a centimeter could equal a foot.

Then divide the drawing into shapes. Squares and rectangles are easiest, followed by triangles and then circles.

Next figure the area of each shape.

For rectangles and squares, multiply width by height.

For triangles, multiply the base by the height and then divide by 2.

For circles, multiply the radius square by 3.1416 (pi). The radius of a circle is the distance from its center point to any other point on the edge of the circle.

Add the areas of all the individual shapes to find the total square footage.

go here

http://www.mathsisfun.com/area.html

My method is not exactly accurate, but it works for me. I take a B&W photo with an electronic camera and load it into a Linux image program called Gimp. The program has a function that tells me what percentage of a B&W image is black or white. The percentage times the size of the object in square feet = your answer.   

applet  for "least squares calculation"

http://www.dartmouth.edu/~chemlab/info/resources/linear/linear.html

enter co-ordinates for each point