Skip over navigation
Diagonals for Area
Age 16 to 18
Challenge Level 
This only uses the result that the area of a triangle is half the base times the height but you need to consider different cases according to whether the quadrilateral is convex or concave.
You may also like
Biggest Bendy
Four rods are hinged at their ends to form a quadrilateral. How can you maximise its area?
So Big
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