Ryan is replacing the ornamental pyramids on top of the fence posts surrounding his yard. they’ve weathered over time. he starts with a block in the shape of a pyramid with a square base. he plans to slice a few inches off its top and sides to make the post toppers safe for his children to play around. in this activity, you’ll look at the cross sections of the pyramid cut by a number of planes in different orientations. part a ryan slices off the top of the pyramid and gets a cross section parallel to the base. what is the shape of this cross section?