1 gen 600 anni - Bramagupta:
Wrote book with ARITHMETIC RULES and had some MISTAKES
Wrote formula for area of cyclic quadrilateral (quadrilaterals in circles):
- where S = perimeter = a+b+c+d
- A = sqrt((s-a)(s-b)(s-c)(s-d))
If d = 0 is area of triangle --> A = sqrt((s-a)(s-b)(s-c))
First to write quadratic formula