"The distance of A and B below H is indicated on the V projection. Thus if to A∧h B∧h the perpendiculars…

"The H projection of the line AB in the space is a line connecting the feet of all the perpendiculars…

"A block revolved from its first position about an axis perpendicular to H through 45 degrees, then…

"The pyramid be revolved about an axis perpendicular to V, the front view will be unchanged and may…

"The pyramid be revolved about an axis perpendicular to V, the front view will be unchanged and may…