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

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

"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).

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.

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…

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…

"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…

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.