Muhammad ibn Muhammad ibn al-Hasan al-Tūsī, better known as Nasir al-Din Tusi, was a Persian polymath, architect, philosopher, physician, scientist, and theologian. One of the greatest scientists of medieval Islam, he is often considered the creator of trigonometry as a mathematical discipline in its own right.
A great work of Islamic Philosophy which let you have a grips on many subjects of it. Besides, it also helps to understand how Islamic Philosophy progressed after Avicenna.