Carl Anton Bretschneider

Carl Anton Bretschneider (27 May 1808 – 6 November 1878) was a mathematician from Gotha, Germany.

Bretschneider worked in geometry, number theory, and history of geometry.

He also worked on logarithmic integrals and mathematical tables.

for Euler's constant when he published his 1837 paper.

He is best known for his discovery of Bretschneider's formula for the area of a general quadrilateral on a plane,

{\displaystyle A={\sqrt {(s-a)(s-b)(s-c)(s-d)-abcd\cdot \cos ^{2}\left({\frac {\alpha +\gamma }{2}}\right)}},}

He is the son of Karl Gottlieb Bretschneider, a theologian.