Formula of butterfly theorem in primary school

Formula of Butterfly Theorem in Primary School: The proportional relationship in any quadrilateral is S 1: S2 = S4: S3 or S 1×S3=S2×S4, and the product of the upper and lower parts is equal to the product of the left and right parts.

Knowledge expansion:

The beauty of natural creatures always gives people a beautiful enjoyment. Just like a butterfly, a symmetrical body and beautiful wings always make people feel very comfortable. Today, we walked into the palace of mathematics together and met another butterfly. Diagonal lines connecting any quadrilateral will divide the quadrilateral into four parts. Its shape is similar to that of a butterfly, and it is called "butterfly model". A series of theorems, called "Butterfly Theorem", are derived from the proportional nature of the area and the edge behind it.