The source of the area
area is formed very early. In ancient Egypt, the Nile rushed once every year, the flood brought fatty silt on both sides, but also wiped the boundaries between fields. The water retired, people must re-export the boundaries of the fields, they must measure the field and calculate the field, so they gradually have an area.
In mathematics, the area problem is to be studied: first specify the area of a square having a side length of 1 is 1, and it is used as a non-self-clear axiom. Then, use such a so-called unit square to measure the other plane geometry. The more simple squares and rectangular areas are easily obtained, and the area problem of parallelogram can be converted into a rectangular area problem with the cutting method, and the area of the triangle can be obtained. Thus, the area of the polygon can be converted into a plurality of triangles.
Area unit
area of the unit generally has the following:
square meter (square centimeter, square rice) - International Standard Unit
Boat - 100 square meters
hectare - 10,000 square meters
square kilometers - 1,000,000 square meters
Marcy:
Square - 0.25 square kilometers
Square Fax - 1/9 square meters
Table system:
Taiwan A -9, 699.173 square meters
Ping - 3.3058 square meters
Hong Kong:
square feet (square foot) < / p>
area calculation formula
A - area R - outer circular radius P-- Semi-week long R-cut circular radius L - circumference length L - arc length
Square:
Rectangle:
Parallel Quadrilateral:
Triangle:
Trapezoid:
Normal hexagon:
sector:
circle:
ellipse: