Illustration used to show "The two perpendiculars to the sides of an angle from any point not in its…

Illustration of polyhedral angle. "The opening of three or more planes which meet at a common point…

An illustration showing a straight angle. When the sides of an angle extend in opposite directions,…

Trihedral angle. "The sum of any two face angles of a trihedral angle is greater than the third face…

An illustration of two angles that are adjacent. They have the same vertex and a common side between…

Illustration of 3 equal dihedral angles. "Two dihedral angles have the same ratio as their plane angles."

Illustration used to show that two trihedral angles are equal or symmetrical when the three face angles…

An illustration showing when one straight line meets another straight line and makes the adjacent angles…

Vertical angles are when two angles have the same vertex, and the sides of the one are prolongations…

"When the minor axis is at least two-thirds the major, the following method ma be used: Make CF and…

"Distribution of magnetic lines through a ring armature. Since the lines follow the metal of the ring…

"Produced by lines drawn vertically, by others drawn diagonally, or by a compound of Paly and Bendy."—Aveling,…

Illustration showing a circle with a diameter, radius, lines, triangle, and segment drawn.

Illustration showing the diameter of a circle inscribed in a right triangle is equal to the difference…

Illustration showing a circle with an inscribed triangle and radii.

Illustration showing a circle with various chords and tangents drawn.

Illustration showing a circle with various chords and tangents drawn.

Illustration where one leg of a right triangle is the diameter of a circle. The tangent at the point…

Illustration showing that from any point in the circumference of a circle, a chord and a tangent are…

Illustration showing 2 intersecting circles with a line drawn through each point of intersection terminated…

Illustration showing 2 intersecting circles with a lines drawn that form a triangle.

Illustration showing 2 circles with that touch each other and two lines drawn through the point of contact…

"If a sector revolves about its bounding radius as an axis, it generates what may be called a spherical…

Illustration of the construction used to bisect a given angle.

Illustration of the construction used to bisect a given line.

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

Illustration to let fall a perpendicular upon a given line from a given external point.

Illustration of the construction of a perpendicular to a line when given a point O on the straight line.

Illustration of the construction of a perpendicular to a line when given a point B on the straight line.

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…

"Any noncircular curve may be approximated by tangent circle arcs, selecting a center by trial, drawing…

The illustration of an irregular curves for solid. The isometric projection of the curve can be drawn…

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

Illustration used to show how to divide a given straight line into required number of equal parts.