=20×20÷2+ 12× 12-(20+ 12)× 12÷2

=200+ 144- 192

= 152 (m2)

or

The shaded part is two triangles, and the height is: (the height of the bottom 5 of the blank right triangle)

4×3÷2×2÷5=2.4 cm

Shaded areas are:

7×2.4÷2=8.4(cm？ )

Extended data:

When the space occupied by an object is a two-dimensional space, the size of the space occupied is called the area of the object, which can be plane or curved.

Area is a quantity indicating the degree of a two-dimensional figure or shape or plane layer in a plane. A surface region is a simulation on a two-dimensional surface of a three-dimensional object. Area can be understood as the amount of material with a given thickness, which is necessary to form a shape model.

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