I. Transformation method

This method transforms irregular graphics into regular graphics with equal area through equal product transformation, translation, rotation and cutting, and then calculates the area of irregular graphics by using the area formula of regular graphics.

Second, the sum-difference method

Some graphics have complicated structures. Through observation, we analyze which regular patterns constitute the area of irregular patterns, and then use the sum or difference of these regular patterns to find them, thus simplifying the complex.

Thirdly, overlapping residual method (including and excluding principle)

It is a method that transforms the area problem of the shadow part into the overlapping part of the regular figure with area, and then uses the "incompatibility principle" (sa∪b = sa+s b-sa∪b) to solve it. The shadow of this kind of problem is generally composed of several figures superimposed. It is necessary to accurately identify its structure and straighten out the size relationship between graphics.

Fourthly, complementary method.

Fill the irregular figure into a special figure, and use the area of the special figure to find the area of the original irregular figure.

Five, splicing method (dig and fill method)

This method is to disassemble the irregular figure, reassemble it into a new figure according to the specific situation and the needs of calculation, and try to find out the area of this new figure.

Six, the special position method

This method is to cut a part of a figure and move it to the appropriate position in parallel, so that it can be combined into a new basic regular figure, which is convenient for calculating the area.