ClipArt ETC
Illustration to show that if through any point in the bisector of an angle a line is drawn parallel to either of the sides of the angle, the triangle thus formed is isosceles.

Angle Bisector Drawn Parallel to A Side

Illustration to show that if through any point in the bisector of an angle a line is drawn parallel…

An illustration of a plane angle with vertex E and sides EF and ED.

Plane Angle

An illustration of a plane angle with vertex E and sides EF and ED.

An illustration showing when one straight line meets another straight line and makes the adjacent angles equal, each of these angles is called a right angle.

Right Angles With Same Vertex

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

An illustration of angles with the same vertex made up of 4 lines.

Angles With Same Vertex

An illustration of angles with the same vertex made up of 4 lines.

"Profile and vertex views of cerebrum. Dr, the frontal lobe; Par, parietal; Oc, occipital; Ts, temporo-sphenoidal lobe; SS, Sylvian fissure; RR, fissure of Rolando; PO, parieto-occipital fissure; IP, intra-pariental fissure; PP, Parallel fissure; SF and IF, supero- and infero-frontal fissures; 1, inferior, 2 middle, and 3, superior frontal convolutions; 4, ascending frontal convolution; 5, ascending parietal, 5', postero-parietal, and 6, angular convolutions; A, supra-marginal, or convolution of the parietal eminence; 7, superior, 8, middle, and 9, inferior temporo-sphenoidal convolutions; 10, superior, 11, middle, and 12, inferior occipital convolutions." — Encyclopedia Britanica, 1893

Brain

"Profile and vertex views of cerebrum. Dr, the frontal lobe; Par, parietal; Oc, occipital; Ts, temporo-sphenoidal…

Illustration of a plane passing through the vertex of a cone (section made is a triangle).

Plane Passing Through the Vertex of a Cone

Illustration of a plane passing through the vertex of a cone (section made is a triangle).

Illustration of a plane passing through the vertex of a cone (section made is a triangle).

Plane Passing Through the Vertex of a Cone

Illustration of a plane passing through the vertex of a cone (section made is a triangle).

Illustration showing that can be used to prove that the base angles of an isosceles triangle are equal.

Base Angles In An Isosceles Triangle

Illustration showing that can be used to prove that the base angles of an isosceles triangle are equal.

Illustration showing that if equal segments measured from the vertex are laid off on the arms of an isosceles triangle, the lines joining the ends of these segments to the opposite ends of the base will be equal.

Equal Segments In An Isosceles Triangle

Illustration showing that if equal segments measured from the vertex are laid off on the arms of an…

Illustration showing that if equal segments prolonged through the vertex are laid off on the arms of an isosceles triangle, the lines joining the ends of these segments to the opposite ends of the base will be equal.

Equal Segments In An Isosceles Triangle

Illustration showing that if equal segments prolonged through the vertex are laid off on the arms of…

Illustration showing that if equal segments measured from the end of the base are laid off on the base of an isosceles triangle, the lines joining the vertex of the triangle to the ends of the segments will be equal.

Equal Segments In An Isosceles Triangle

Illustration showing that if equal segments measured from the end of the base are laid off on the base…

Illustration showing that if equal segments measured from the end of the base prolonged are laid off on the base of an isosceles triangle, the lines joining the vertex of the triangle to the ends of the segments will be equal.

Equal Segments In An Isosceles Triangle

Illustration showing that if equal segments measured from the end of the base prolonged are laid off…

"A pyramid is a solid whose base is a polygon, and whose sides are triangles uniting at a common point, called the vertex." —Hallock 1905

Pryamid

"A pyramid is a solid whose base is a polygon, and whose sides are triangles uniting at a common point,…

Illustration to show the bisector of the vertical angle of a triangle makes with the perpendicular from the vertex to the base an angle equal to half the difference of the base angles.

Triangle With Bisector and Perpendicular From Vertex Drawn

Illustration to show the bisector of the vertical angle of a triangle makes with the perpendicular from…

Illustration to show that if one of the legs of an isosceles triangle is produced through the vertex by its own length, the line joining he end of the leg produced to the nearer end of the base is perpendicular to the base.

Leg Produced through the Vertex of an Isosceles Triangle

Illustration to show that if one of the legs of an isosceles triangle is produced through the vertex…

Illustration to show lines drawn from the vertices to join at a point within the triangle.

Triangle With Lines From the Vertices That Join a Point Within

Illustration to show lines drawn from the vertices to join at a point within the triangle.