What are the answers to these two questions?

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?

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

Graph the equationy=x^2 -[tex]y = x^{2} - 2[/tex]