Illustration showing various circles and the angles formed by intersecting lines.

A pilot's cockpit from a propeller aeroplane, or airplane. The diagram illustrates the different parts…

An instrument consisting essentially of a dipping needle, a verticle graduated circle whose center coincides…

Illustration of a right circular cone resting on an element such that the vertex is on the bottom and…

Illustration of the construction used to escribe circles with centres (centers) called ex-centres of…

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

Illustration of the construction used to make a triangle when given a side and two angles.

Illustration that can be used to show that if the cotangent of an angle is negative the angle must terminate…

Illustration of blueprint used by highway engineers to widen the pavement on the inside of the curve…

Illustration showing an angle of depression from a horizontal line to a line of sight.

A design of the propeller airplane, or aeroplane, in flight with a higher tail to create an angle of…

A propeller airplane, or aeroplane, design with a high tail. This design creates a larger angle of incidence…

Illustration of a propeller aeroplane, or airplane, with lower tail in flight.

The propeller airplane, or aeroplane, design in fast landing. This design requires a large landing area…

Diagram used to prove the theorem: "Every point in a plane which bisects a dihedral angle is equidistant…

The 45-degree triangle can be used to make a line at a multiple of 15 degrees.

Illustration showing an angle of elevation from a horizontal line to a line of sight.

An illustration showing the construction used to erect an equal angle. "With D as a center, draw the…

A plane flying above land illustrating the use of ailerons to adjust the angle of incidence to adjust…

An airplane flying above the show illustrating the aerodynamics of the plane with the tail wing at the…

An illustration of the plane flying over land from point A to B by flying the plane with the direction…

"An inclined plane is a slope, or a flat surface, making an angle with a horizontal line...the force…

An illustration showing a model of 2 circles with tangent lines, diameters, and radii that illustrates…

An illustration showing a model of 2 circles with tangent lines, diameters, and radii that illustrates…

An illustration showing a model of a circle with an exterior angle formed between a tangent and a secant…

An illustration showing a model of a circle with angles formed between tangents and secants that illustrates…

Illustration modeling the illumination on a surface when the surface is not perpendicular to hte rays…

Illustration that can be used to show that when given an angle, expressed as an inverse function of…

To find the angle between two given lines a, b of which the projections a1, b1 and a2, b2 are given.

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

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 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…

"The circles for position angle and declination are read by micrometer microscopes illuminated by the…

Illustration showing a circle inscribed in a regular pentagon. Or, a regular pentagon circumscribed…

"If two angles not in the same plane have their sides respectively parallel and lying in the same direction,…

"A prism is a transparent body with two refraction surfaces that lie in intersecting planes. The angle…

"Cathetal prisms readily yield the phenomena of total reflection as shown, and are often used when light…

Diagram used to prove the theorem: "Two prisms are equal when the three faces about a trihedral of one…