Think about the requirements for different shapes. What shape has these requirements?
Look at the diagram. What do these lines do?
They are perpendicular and intersect each other at their midpoints. They also bisect the angles of the quadrilateral.
Find the area of one of the triangles, then find the total area. What do you know about the triangles that can help you?
The angles at the center are 90°, so it is a 30−60−90 triangle.