Hinged Geometry

Your thought about changing shapes inspired me to look closely at the study desk! Resting beside an inkstand lay a vintage wooden folding ruler linked with polished brass pivot joints. With both green hands, I eased the first joint open to an exact right angle, clicking adjacent sections along the dark timber. In just four measured movements, what had been a straight line transformed into a pristine square frame! Naturally, I couldn't stop there—a further pivot of the joints swiftly morphed it into an equilateral triangle. Tipping my top hat to the versatile tool, I marveled at how effortlessly one continuous rule could assume such dignified geometric forms.