ABCD is a cyclic quadrilateral such that AB is 7 , BC is 24 , CD is 15 and DA is 20 units respectively. points E and F lie on AC such that AE=EF=FC . what is the area of the quadrilateral BEDF.

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- Feb 13th 2013, 12:06 AMgeniusgarviltrisecting diagonal
ABCD is a cyclic quadrilateral such that AB is 7 , BC is 24 , CD is 15 and DA is 20 units respectively. points E and F lie on AC such that AE=EF=FC . what is the area of the quadrilateral BEDF.

- Feb 13th 2013, 12:46 AMearbothRe: trisecting diagonal
1. By first inspection:

That means AC = 25 and ABCD consists of 2 right triangles with a common hypotenuse.

2. The long way: In a cyclic quadrilateral the interior angles of opposite vertices add up to 180° (or pi).

Use Cosine rule:

Solve this system of equations for x and AC.

3. Let a denote the area. Then