Illustration of two lines intersecting at a point. This can be used to show vertical angles.

Illustration showing two straight lines drawn from the same point in a perpendicular to a given line,…

Illustration showing two lines CA and CB drawn from the point C to the extremities of the straight line…

Illustration of two straight lines drawn from a point in a perpendicular to a given line, cutting off…

Illustration showing only one perpendicular can be drawn to a given line from a given external point.

Illustration showing two straight lines in the same plane perpendicular to the same straight line are…

Illustration showing if a straight line is perpendicular to one of two parallel lines, it is perpendicular…

Illustration of two parallel lines with equal segments between them. Two parallel lines are everywhere…

Illustration showing that a transversal is a straight line that cuts two or more straight lines.

Illustration showing that when three or more parallel lines intercept equal parts on one transversal,…

Illustration showing that if two parallel lines are cut by a transversal, then the alternate interior…

Illustration showing that when two straight lines in the same plane are cut by a transversal, if the…

Illustration showing that when two parallel lines are cut by a transversal, the exterior-interior angles…

Illustration showing that when two parallel lines are cut by a transversal, the two interior angles…

An exercise problem to create a vanishing point using lines. The line is drawn by placing a dot into…

"Experiment showing lines of force in the magnetic field surrounding a conductor carrying an electric…

A marking gauge is used in woodworking and metalworking to mark out lines for cutting or other operations.…

"Illustrating Maxwell's 'corkscrew rule' for relative directions of current and lines of force...a current…

Oval with dotted vertical and horizontal lines that are lines of symmetry.

Illustration of the construction used to create a line parallel to a given line.

Illustration showing two parallel vertical lines cut by a perpendicular line and a transversal. Congruent…

A perpendicular line drawn from point P to straight line RS.

"The locus of a point in space equidistant from the extremities of a straight line is the plane perpendicular…

If a straight line is perpendicular to each of two other straight lines in a plane at their point of…

Straight line AB is perpendicular to the lines in plane MN at point B. "If from the foot of a perpendicular…

Two straight lines, AB and CD, perpendicular to the same plane (MN) are parallel.

"Through a given line oblique to a plane, one, and only one plane, can be passed perpendicular to the…

Two intersecting planes on a third plane. "If two intersecting planes are each perpendicular to a third…

Illustration of two parallel planes. "Two planes perpendicular to the same straight line are parallel."

Two parallel planes perpendicular to a line (AB). "A straight line perpendicular to one of two parallel…

CD is the projection of AB upon OX. In each case AE=CD and AE=ABcos theta.

Illustration of an axis of symmetry drawn with respect to a quadrilateral.

Illustration of a quadrilateral which has two adjacent sides equal and the other two sides equal. It…

One of a series of small ropes or lines which transverse the shrouds horizontally, thus forming steps…

"Fleming's rule for direction of induced current. Extend the thumb, forefinger and middle finger of…

"Nodal Cubic, with four primary lines and their satellite. In the diagram, ABC is the satellite line.…

Illustrations of a segment, a ray, and a line that can be used when providing definitions.

A heraldic shield with a black surface, which is shown by the crossing horizontal and vertical lines.

A line with arrows on both ends to show that it extends indefinitely. The line is slanting up when read…

A line with arrows on both ends to show that it extends indefinitely. The line is slanting down when…

A line with arrows on both ends to show that it extends indefinitely. The line is slanting up when read…