Define the following terms:

- vanishing point
- orthogonal
- picture plane

vanishing point- A vanishing point is a point on the image plane of a perspective drawing where the two-dimensional perspective projections (or drawings) of mutually parallel lines in three-dimensional space appear to converge.

orthogonal- elating to or involving lines that are perpendicular or that form right angles, as in This design incorporates many orthogonal elements. Another word for this is orthographic. When lines are perpendicular, they intersect or meet to form a right angle.

picture plane- in perspective, the imaginary plane corresponding to the surface of a picture, perpendicular to the viewer's line of sight.

i think it's about 10 mins.

actually i think that's wrong, but i don't know how to delete this.

but who knows it might be right.