The study of Trigonometry was first started in India. The ancient Indian mathematicians Aryabhatta (A.D 476),Bhaskara I(A.D 600), Bhaskara(A.D 1114)and Brahmagupta(A.D 598) got important results. All this knowledge first went from India to Middle East and from there to Europe. The Greeks had also started the study of trigonometry but their approach was so clumsy that when the Indian approach became known, it was immediately adopted throughout the world.
In India, the predecessor of the modern trigonometric function, known as the sine of an angle, and the introduction of the sine function represents the main contribution of the sidhantas to the history of mathematics.
Baskara I gave formula to find the values of sine function for angles more than 90 degree.
The name of Thales (A.D 600) is associated with height and distances problems. He is credited with the determination of the height of pyramid in Egypt by measuring shadows of the pyramid using similarity property.