You are trying to prove that quadrilateral abcd is a rhombus. you know that both pairs of opposite sides are parallel (a parallelogram). which additional fact would prove that abcd is a rhombus?

A3-dimensional figure has a square base and 4 lateral faces that meet at a point. explain the difference between the cross sections when a slice is made perpendicular to the base through the vertex, and when a slice is made perpendicular to the base and not through the vertex