Do you have enough information to work out the area of the shaded quadrilateral?
Four rods are hinged at their ends to form a quadrilateral. How can you maximise its area?
One side of a triangle is divided into segments of length a and b by the inscribed circle, with radius r. Prove that the area is: abr(a+b)/ab-r^2
Prove that the area of a quadrilateral is given by half the product of the lengths of the diagonals multiplied by the sine of the angle between the diagonals.