Circle in Quadrilateral
Constructing circles within quadrilaterals
The four green points are the vertices of a quadrilateral.
The orange, blue and yellow points can be moved, changing the shape of the quadrilateral.
The quadrilateral usually contains a circle touching all four of its sides.
Explore and take note of your observations ...
Source: https://pdst.ie/sites/default/files/S%26S%20manual_22.11.13.pdf, page 157.