1, the formula for calculating the area of shoelaces is s = (x1* y2+x2 * y3+x3 * y1* x2-y2 * x3-y3 * x1)/2. Users cross multiply the corresponding coordinates to find the area around the polygon, and subtract the area from the surrounding polygons to find the area of the polygon.
2. It is called shoelace formula because the coordinates that make up the polygon are constantly cross-multiplied, just like tying shoelaces. First of all, with an example, how to calculate the area of polygon by shoelace theorem is explained. We just need to select a vertex, then read the coordinates counterclockwise, and finally return to the starting point. And connect the coordinates in series in an order similar to tying shoelaces. ?
3. It is a formula for directly calculating the area of a triangle by using the side lengths of three sides of the triangle. It is characterized by beautiful form and easy memory. According to legend, this formula was first drawn by the ancient Greek mathematician Archimedes. Because this formula first appeared in Helen's book Geodesy, it was called Helen's formula. China and Qin also put forward a similar formula, which is the so-called triclinic quadrature.