Brahmagupta is widely regarded as the father of Indian geometry due to his significant contributions to the field, including his work on the geometry of circles.

Brahmagupta's theorem is a significant result in the geometry of circles that establishes a relationship between the diagonals and sides of a cyclic quadrilateral.

Aryabhata was the first Indian mathematician to discover the concept of the circumcircle of a triangle, which is the circle that passes through all three vertices of the triangle.

Bhaskara's theorem is a fundamental result in the geometry of circles that establishes a relationship between the angles formed by a tangent, a chord, and a diameter.

Bhaskara II is credited with discovering the concept of the incircle of a triangle, which is the circle that lies inside the triangle and is tangent to all three sides.

Descartes' theorem is a significant result in the geometry of circles that establishes a relationship between the lengths of tangents drawn from a point outside a circle and the distance from the point to the center of the circle.

Brahmagupta discovered the concept of the excircle of a triangle, which is the circle that lies outside the triangle and is tangent to one side and the extensions of the other two sides.

Brahmagupta's theorem is a significant result in the geometry of circles that establishes a relationship between the sides and diagonals of a cyclic quadrilateral.

Bhaskara II is credited with discovering the concept of the radical axis of a system of circles, which is the line that is perpendicular to the common chords of the circles and passes through their centers.

Thales' theorem is a fundamental result in the geometry of circles that establishes a relationship between the angles formed by a tangent, a chord, and a diameter.

Brahmagupta discovered the concept of the nine-point circle of a triangle, which is the circle that passes through the midpoints of the sides, the feet of the altitudes, and the midpoints of the segments joining the orthocenter to the vertices of the triangle.

Brahmagupta's theorem is a significant result in the geometry of circles that establishes a relationship between the diagonals and sides of a cyclic quadrilateral.

Bhaskara II is credited with discovering the concept of the power of a point with respect to a circle, which is the square of the distance from the point to the center of the circle minus the square of the radius of the circle.

Thales' theorem is a fundamental result in the geometry of circles that establishes a relationship between the angles formed by a tangent, a chord, and a diameter.

Bhaskara II discovered the concept of the pedal circle of a triangle, which is the circle that passes through the feet of the perpendiculars drawn from a point outside the triangle to the sides of the triangle.