The radius of in-circle is given by the formula DERIVATION
Derivation of Formula for Radius of Circumcircle
The formula for the radius of the circle circumscribed about a triangle (circumcircle) is given by
Derivation of Formula for Area of Cyclic Quadrilateral
For a cyclic quadrilateral with given sides a, b, c, and d, the formula for the area is given by DERIVATION OF THE FORMULA
