On this day, 300 years ago, on August 26, 1725 (July 19, 1725 lunar calendar), the German mathematician and physicist Lambert was born. Lambert (JohannHeinrichLambert) (August 26, 1728 - September 25, 1777), a German mathematician. His father was a tailor. To study, at the age of 12, he helped his father work and studied by himself at dusk. Since the age of 15, Lambert has worked as a clerk, a newspaper secretary, and a private tutor. As a private tutor, he used the vast library of his proprietor for his studies. The study of optics first introduced hyperbolic functions to trigonometry to study the phenomena of non-Euclidean geometry, including the angles and areas of hyperbolic triangles. Proved that ¦Ð is an irrational number. Commentary: A very impressive mathematical genius, much of his knowledge was self-taught.