# Geometría proyectiva: Intersection of straight and tapered

Projective definition of the conical allowed to start solve classical problems of identification of new elements of the conical (new points and tangents in them), and find the intersection with a line or a tangent from an external point. These problems can be solved by various more or less complex methods and conceptually more or less laborious paths.

We will now see how to determine the two possible intersection points of a line with a taper defined by five points.

# Diédrico System: True magnitude of the line

By projecting a straight line on a plane orthogonal projection, its projection, generally, is smaller than the original measure.

Given a straight (segment bounded by two points) we want to determine its true magnitude and the angle it makes with the planes of projection.

# Diédrico System: Third straight projection

The main projections on two planes straight dihedral (horizontal and vertical planes) possible to determine other new planes orthogonal projections on.

We'll see how generically determine a new projection from two. Later we will consider your application to study the so-called “auxiliary projections”, influencing their usefulness in solving various problems.

# Diédrico System: Projection of the line

After seeing the foundations of Diédrico System, with the projection of a point on two planes orthogonal projection, let's see how you can wean the system of land line as we have two or more points. This system called “Free System” is more flexible than the traditional because Monge, giving prominence to the reference lines and guiding the conceptual model to a more constructive and less spatial geometry.