In a pentagon ABCDE, diagonal AD is parallel to the side BC and the diagonal CE is parallel to the side AB. Show that the areas of the triangles △ABE and △BCD are the same.
The figure below is a regular pentagram. What is larger, the black area or the blue area?
A circle was inscribed in a square, and another square was inscribed in the circle. Which area is larger, the blue or the orange one?
Let E and F be the midpoints of the sides BC and AD of the parallelogram ABCD. Find the area of the quadrilateral formed by the lines AE,ED,BF and FC, if it is known that the area ABCD is equal to S.