Surface area of an oblique cut in Electromagnetism

Question

If anyone is interested, my concern is related to page 176

Introduction to electrodynamics by Griffiths

Griffiths mentioned that the surface of the oblique cut is the product of surface area at the end $A_{end}$ and $Cos\left ( \theta \right )$. I do not quite understand the intuition involved here. Regardless of an oblique cut, isn't the surface area the same?

Any help is appreciated.

Thanks in advance.