On the afternoon of June 7th, 2015, two nouns "biē nào" and "Yang Ma" appeared in a geometry question in the mathematics volume of Hubei liberal arts in the 2065 438+05 college entrance examination. Ancient Chinese characters appeared in the math exam, which quickly spread on the Internet and became a hot topic. Question 20 of liberal arts mathematics involves the knowledge in "Nine Chapters of Arithmetic and Business". First of all, explain what "turtle" and "mother" are, and solve the problem according to these two words and related materials.

(20 15, Hubei, 20, 13) In the nine chapters of arithmetic, a quadrilateral with a rectangular bottom and a side perpendicular to the bottom is called Ma Yang, and a tetrahedron with four right triangles is called turtle. As shown in the figure, in Mayang P-ABCD, side PD⊥ bottom ABCD, PD=CD, and point E is the midpoint of PC, connecting de, BD and BE.

(1) Proof: DE⊥ Plane PBC. Try to judge whether the tetrahedron EBCD is a turtle. If yes, write the right angle of each face (only write the conclusion); If not, please explain the reasons;

(2) Remember that the volume of Mayang P-ABCD is V 1, and the volume of tetrahedral EBCD is V2, and find the value of V 1/V2.