5.3.1.10 Construction of secrets

Condition: side of the base \ (a b c d \) the correct pyramid \ (s a b c d \) is 2, the length of the lateral rib is \ (\ sqrt {10} \). On the ribs \ (s a \) and \ (s d \) points \ (e \) and \ (f \) are located so that \ (s e = 5 a e \), \ (d f = 2 s f \). Through the points \ (e \) and \ (f \) a plane \ (\ alpha \), parallel \ (C D \), was drawn. Find the area of the section.