Sumerian astronomers introduced angle measure, using a division of circles into 360 degrees. They and their successors the Babylonians studied the ratios of the sides of similar triangles and discovered some properties of these ratios, but did not turn that into a systematic method for finding sides and angles of triangles. The ancient Nubians used a similar method. The ancient Greeks transformed trigonometry into an ordered science. http://en.wikipedia.org/wiki/Trigonometry<quoted text>
Actually, the record here is varied. Some used the degrees derived from Babylonian sources. Others used what was essentially radian measures. Hipparchus, as I recall, used a radius for his standard circle so that angular masures came out nicely. Ptolemy used something closer to degrees.
And for radians ?