Al-Kashi, Jamshid (1380 - 1429)

Jamshid al-Kashi was a Persian astronomer and mathematician. He is created with being the first to state the law of cosines in a form for triangles. He wrote The Treatise on the Chord and Sine which computed the sine of one degree to a level of accuracy that was not surpassed until the 16th century. He estimated 2pi to 17 decimals places, an accuracy not surpased for nearly 200 years.

Stamps

Stamp	Description
	Iran, 5r, 1979 Scott: 2042 A545