Correct solutions came from BU students Colin Schulties, Kirstin Jerzy, Rob Andry and alumnus Will Shelton. Correct solutions were sent in by Juan Carlos Marivela, Spain; Philippe Fondanaiche, France; Bill Webb, USA; Farid Lian, Colombia; Ron Welch, USA; Jerome Cherry; Yunting GAO, China; Jack Tseng; Ahron Teitelman, Israel; Lou Cairoli, USA; Claudio Baiocchi, Italy.
Using the fact that this is a quadrilateral
and that ab
= 1/4, we only need to determine bt.
Using Pythagoras, we have