Brahmagupta was a renowned Indian mathematician and astronomer who lived in the 6th century CE. He made significant contributions to geometry, including the development of the Brahmagupta formula for calculating the area of a cyclic quadrilateral.

Brahmagupta's formula is a mathematical formula used to calculate the area of a cyclic quadrilateral, which is a quadrilateral whose vertices all lie on a circle.

Brahmagupta's formula for calculating the area of a cyclic quadrilateral is given by the formula $$Area = \sqrt{(s - a)(s - b)(s - c)(s - d)}$$, where 's' is the semi-perimeter of the quadrilateral and 'a', 'b', 'c', and 'd' are the lengths of its sides.

Brahmagupta's theorem states that in a cyclic quadrilateral, the sum of the squares of the diagonals is equal to the sum of the squares of its sides.

Brahmagupta's theorem is expressed by the formula $$a^2 + b^2 + c^2 + d^2 = 2(AC^2 + BD^2)$$, where 'a', 'b', 'c', and 'd' are the lengths of the sides of the cyclic quadrilateral and 'AC' and 'BD' are the lengths of its diagonals.

Bhaskara II was a renowned Indian mathematician and astronomer who lived in the 12th century CE. He made significant contributions to geometry, including the development of the Bhaskara's formula for calculating the area of a triangle.

Bhaskara's formula is a mathematical formula used to calculate the area of a triangle.

Bhaskara's formula for calculating the area of a triangle is given by the formula $$Area = \sqrt{s(s - a)(s - b)(s - c)}$$, where 's' is the semi-perimeter of the triangle and 'a', 'b', and 'c' are the lengths of its sides.

Bhaskara's theorem states that in a cyclic quadrilateral, the sum of the squares of the sides is equal to the sum of the squares of its diagonals.

Bhaskara's theorem is expressed by the formula $$a^2 + b^2 + c^2 + d^2 = AC^2 + BD^2$$, where 'a', 'b', 'c', and 'd' are the lengths of the sides of the cyclic quadrilateral and 'AC' and 'BD' are the lengths of its diagonals.

Aryabhata was a renowned Indian mathematician and astronomer who lived in the 5th century CE. He made significant contributions to geometry, including the development of the Aryabhata's formula for calculating the area of a triangle.

Aryabhata's formula is a mathematical formula used to calculate the area of a triangle.

Aryabhata's formula for calculating the area of a triangle is given by the formula $$Area = \frac{1}{2}bh$$, where 'b' is the length of the base of the triangle and 'h' is the height of the triangle.

Pythagoras' theorem states that in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.

Pythagoras' theorem is expressed by the formula $$a^2 + b^2 = c^2$$, where 'a' and 'b' are the lengths of the two shorter sides of the right triangle and 'c' is the length of the hypotenuse.