Plane ABF and plane FHG are parallel perpendicular intersec

Plane ABF and plane FHG are ___ parallel perpendicular intersecting but not perpendicular skew

ans;perpendicular .

these two planes are in 90 degrees with each other. the plane ABF is on top plane on rectangular and plane fgh is on vertical side of the rectangular thats y if we calculate the angle of these two planes are in 90 degrees. since the answer is perpendicular.