Aryabhata is widely regarded as the father of Indian trigonometry due to his groundbreaking work in the 5th century CE.

Aryabhata introduced the concept of sine and cosine functions, known as 'jya' and 'koti-jya' respectively, in his treatise 'Aryabhatiya'.

Brahmagupta's formula is a trigonometric identity that relates the sine and cosine of an angle to the sine and cosine of its complement.

Bhaskara II introduced the concept of the tangent function, known as 'sparsha', in his work 'Lilavati'.

Madhava of Sangamagrama developed the series expansion for sine and cosine functions, which later became known as the Taylor series.

Madhava of Sangamagrama compiled a trigonometric table containing the values of sine and cosine functions for various angles.

Bhaskara II introduced the concept of the secant and cosecant functions, known as 'secha' and 'cosecha' respectively, in his work 'Lilavati'.

Bhaskara II introduced the concept of the cotangent function, known as 'cotangent', in his work 'Lilavati'.

Bhaskara II introduced the concept of the versine function, known as 'versed sine', in his work 'Lilavati'.

Madhava of Sangamagrama discovered an identity that relates the sine and cosine functions to the tangent function, which is known as Madhava's identity.

Madhava of Sangamagrama introduced the concept of the haversine function, which is defined as half the versine function.

Madhava of Sangamagrama discovered an identity that relates the sine and cosine functions to the haversine function, which is known as Madhava's identity.

Madhava of Sangamagrama introduced the concept of the exsecant and excosecant functions, which are defined as the reciprocals of the secant and cosecant functions respectively.

Madhava of Sangamagrama discovered an identity that relates the sine and cosine functions to the exsecant and excosecant functions, which is known as Madhava's identity.