Illustration of supplementary angles. Two angles whose sum is a straight angle.

Supplementary Angles

Illustration of supplementary angles. Two angles whose sum is a straight angle.

Illustration of supplementary angles. Two angles whose sum is a straight angle. This can be used tow show the Theorem: If two adjacent angles have their exterior sides in a straight line, these angles are supplementary.

Supplementary Angles

Illustration of supplementary angles. Two angles whose sum is a straight angle. This can be used tow…

Illustration of supplementary angles. Two angles whose sum is a straight angle. This can be used tow show the Theorem: If two adjacent angles are supplementary, their exterior sides are in the same straight line.

Supplementary Angles

Illustration of supplementary angles. Two angles whose sum is a straight angle. This can be used tow…

Illustration that can be used to show supplementary angles. The angles form a straight line.

Supplementary Angles

Illustration that can be used to show supplementary angles. The angles form a straight line.

Illustration of a circle which illustrates that through three points not in a straight line one circumference, and only one, can be drawn.

Circle With Circumference Through Three Points

Illustration of a circle which illustrates that through three points not in a straight line one circumference,…

Illustration of a circle which illustrates that the tangents to a circle drawn from an external point are equal, and make equal angles with the line joining the point to the center.

Circle With Two Tangents Drawn From an External Point

Illustration of a circle which illustrates that the tangents to a circle drawn from an external point…

Illustration of the construction used to create an equal angle given a point in a given straight line and a given angle.

Construction of an Equal Angle Given a Point and a Straight Line

Illustration of the construction used to create an equal angle given a point in a given straight line…

Illustration of the construction used upon a given straight line, to describe a segment of a circle in which a given angle may be inscribed.

Construction to Describe a Segment of a Circle in Which an Angle Can Be Inscribed

Illustration of the construction used upon a given straight line, to describe a segment of a circle…

Illustration of the construction used to divide a straight line into a given number of equal parts.

Construction of a Straight Line Divided Into Equal Parts

Illustration of the construction used to divide a straight line into a given number of equal parts.

Illustration of the construction used to create straight line parallel to a given straight line through a given external point.

Construction of a Straight Line Parallel to a Given Straight Line

Illustration of the construction used to create straight line parallel to a given straight line through…

An exercise for mechanical drawing to construct a series of horizontal lines. The solid lines are drawn without using a T square, while the dashed lines are produced using a T square.

Horizontal Solid and Dashed Line Drawing Exercise

An exercise for mechanical drawing to construct a series of horizontal lines. The solid lines are drawn…

An exercise problem drawing a series of horizontal lines using a straight edge or triangle without using a T square.

Horizontal Solid Line Drawing Exercise

An exercise problem drawing a series of horizontal lines using a straight edge or triangle without using…

Illustration showing that the perpendicular is the shortest line that can be drawn to a straight line from an external point.

Perpendicular Line Drawn To a Given Line From an External Point

Illustration showing that the perpendicular is the shortest line that can be drawn to a straight line…

Straight line

Straight Line

Straight line

An illustration of a straight line/segment.

Straight Line

An illustration of a straight line/segment.

Illustration of a straight line.

Straight Line

Illustration of a straight line.

An illustration of a straight line with 5 points dividing it into 4 equal parts. Multiple of a given line.

Straight Line With Points Divided Into Equal Parts

An illustration of a straight line with 5 points dividing it into 4 equal parts. Multiple of a given…

An illustration of a straight line with a point.

Straight Line With Point

An illustration of a straight line with a point.

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

Intersecting Straight Lines

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, cutting off on the line unequal segments from the foot of the perpendicular, the more remote is the greater.

Lines Drawn From the Same Point in a Perpendicular to a Given line, Cutting Off Segments

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 AB. OA and OB are two lines similarly drawn, but included by CA and CB. This can be used to show the theorem: The sum of two lines drawn from a point to the extremities of a straight line is greater than the sum of two other lines similarly drawn, but included by them.

Lines Drawn From the Point C to the Extremities of the Straight line AB

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 on the given line equal segments from the foot of the perpendicular, are equal and make equal angles with the perpendicular. This illustration can be used to show the proof.

Lines Drawn to Another Line to Form Triangle

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.

Perpendicular Line Drawn to a Given Line from an External Point

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 parallel.

Parallel Lines

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 to the other also.

Parallel Lines

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

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

Lines Cut By A Transversal

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, they intercept equal parts on every transversal.

Parallel Lines Cut By A Transversal

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 angles are equal.

Parallel Lines Cut By A 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 alternate interior angles are equal, the two straight lines are parallel.

Parallel Lines Cut By A Transversal

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 are equal.

Parallel Lines Cut By A Transversal

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 on the same side of the transversal are supplementary.

Parallel Lines Cut By A Transversal

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

Illustration of the construction used to make a perpendicular bisector of a straight line.

Construction Of A Perpendicular Bisector Of A Straight Line

Illustration of the construction used to make a perpendicular bisector of a straight line.

Illustration of the construction used to create a perpendicular to a straight line at a given point.

Construction Of A Perpendicular To A Straight Line

Illustration of the construction used to create a perpendicular to a straight line at a given point.

Illustration of the construction used to create a perpendicular to a straight line from a given point not on the line.

Construction Of A Perpendicular To A Straight Line

Illustration of the construction used to create a perpendicular to a straight line from a given point…

To draw a straight line, the pen must be perpendicular with the straight edge ruler, as shown in A. A one sided ragged line will result if the pen is positioned at C. If the pen is positioned at B, the ink will run under the edge and form a blot.

Positioning Pen with the Straight Edge

To draw a straight line, the pen must be perpendicular with the straight edge ruler, as shown in A.…

Illustration showing a triangle with an exterior segment drawn to show and exterior angle. This can be shown to show adjacent angles ACB and ACD as well.

Triangle With Segment Extended for Exterior Angle

Illustration showing a triangle with an exterior segment drawn to show and exterior angle. This can…

Illustration showing a triangle with an interior segment drawn

Triangle With Interior Segment

Illustration showing a triangle with an interior segment drawn