Any principal view shows three of the four principal dimensions.

If an angle is in an inclined plane, it may be projected either larger or smaller than the true angle depending on its position.

If an edge is perpendicular to a plane of projection, it appears as a point.

Visible lines always take precedence over hidden lines or centerlines.

A plane surface that is parallel to a plane of projection appears on edge as a straight line.

First-angle projection is primarily used in Europe and Asia.

Usually screws, bolts, shafts, tubes, and other elongated parts are drawn in a vertical position in the front view.

A normal surface is perpendicular to a plane of projection.

The depth dimensions in the top and side views do not necessarily correspond.

Any object can be viewed from six mutually perpendicular views.

A total of three principal views are arranged in a standard way.

In orthographic views, dashed lines represent features that would be hidden behind other surfaces.

Drawings are two-dimensional representations of objects that allow you to record sizes and shapes precisely.

The profile plane is the plane upon which the side view is projected.

Height is shown in the left-side, top, right-side, and bottom views.

The rear, left-side, front, and right-side views align horizontally.

Width is shown in the rear, top, front, and bottom views.

A plane surface always projects either on edge or as a surface in any view.

This type of surface is tipped to all principal planes of projection and does not appear true size in any standard view:

The top, front, and bottom views align in this manner: