[1] Can you solve this geometry problem (Areas)

Crossed Ladder Theorem

A triangle is divided into four regions by two straight lines. The areas of three of the regions are given. What is the area of the fourth region. (Note: diagram is not drawn to scale)

The solution:

The solution to the puzzle involves a variant of the Crossed Ladder Theorem, which I will call the "Extended Crossed Ladder Theorem", which states ...... continue reading here