How do you find an area of a surface?

Answer 1

It depends on the shape of the surface.

For some shapes - a circle, ellipse, regular polygon, for example - there are formulae that will enable you to calculate the area with a few measurements. Some more complex shapes can be broken down into the above shapes. So if you have a shape like a child's silhouette of a house, you can add the area of the rectangle (building) and the triangle (roof). And another small rectangle, if there is a chimney!

For very irregular shapes, there are two main options. One is to mark the shape out on a regular grid (a graph paper). Count the number of grid squares where half or more is inside the shape, ignore all that are at least half outside the shape. This should give a reasonable estimate of the area. The finer the grid on the graph paper, the more accurate your answer, but also, the more squares you will have to count.

Alternatively, you can weigh the shape (or a copy). Then cut and weigh a unit square (or copy). A comparison of the two weights should enable you to scale the area of the unit square up to the area of the shape.