The diagram shows a pyramid.

is a square with sides of length 10 cm.
The other faces of the pyramid are equilateral triangles with sides of length 10 cm.
Calculate the volume of the pyramid.
Give your answer in the form where and are integers to be found.
Extract:
The diagram shows a pyramid. [B C D E] is a square with sides of length 10 cm. The other faces of the pyramid are equilateral triangles with sides of length 10 cm.
Find the size of angle .


