starting at the top if you cut a square pyramid in half using a single cut, what is the shape of the newly exposed shape
The shape of the newly exposed shape depends on the location and direction of the cut.
If the cut is made horizontally such that it passes through the middle of the pyramid, then the newly exposed shape would be a square. This is because the base of the pyramid is a square, and cutting it in half horizontally would reveal a smaller square base.
If the cut is made vertically through one of the corners of the square base, then the newly exposed shape would be a triangle. This is because the base of the pyramid would be cut diagonally, revealing a triangular base.