How did hipparchus discover trigonometry

This seems to firmly place Hipparchus in Nicaea and indeed Ptolemy does describe Hipparchus as observing in Bithynia, and one would naturally assume that in fact he was observing in Nicaea. However, of the observations which are said to have been made by Hipparchus, some were made in the north of the isla

Hipparchus full name

Hipparchus father of trigonometry

Hipparchus trigonometry table

How did hipparchus die