Tangent to a Catenary
Any tangent to the catenary has the property , where is the tangent to the catenary at , and is the semicircle with center and radius .
 G. N. Berman, A Problem Book in Mathematical Analysis, Moscow, Russia: Mir Publishers, 1957 p. 69.
"Tangent to a Catenary"
Wolfram Demonstrations Project
Published: November 5 2012