Halving the Perimeter of a Heart-Shaped Curve

Requires a Wolfram Notebook System
Interact on desktop, mobile and cloud with the free Wolfram Player or other Wolfram Language products.
A curve consists of two semicircles of radius 1 and one semicircle of radius 2. A chord through the origin and inclination divides the curve into two parts, red and blue. Which curve is longer?
Contributed by: Izidor Hafner (October 2013)
Open content licensed under CC BY-NC-SA
Snapshots
Details
The two parts have equal lengths. The blue part consists of a semicircle of length : arc
of length
and arc
of length
Together, these are
. The length of the whole curve is
. So the dashed line halves the perimeter.
Reference
[1] D. Wells, The Penguin Dictionary of Curious and Interesting Geometry, London: Penguin Books, 1991, p. 30.
Permanent Citation