Describe in words the surface whose equation is given. φ = π/4 (select the correct answer)
1)the top half of the right circular cone with vertex at the origin and axis the positive z-axis
2)the plane perpendicular to the xz-plane passing through z = x, where x ≥ 0
3)the plane perpendicular to the xy-plane passing through y = x, where x ≥ 0
4)the base of the right circular cone with vertex at the origin and axis the positive z-axis
5)the plane perpendicular to the yz-plane passing through z = y, where y ≥ 0