2. The Supplement of an arc is 180° minus the arc.
3. The Sine of an angle, or of an arc, is a line drawn from one end of an arc, perpendicular to a diameter drawn through the other end.
4. The Cosine of an arc is the perpendicular distance from the center of the circle to the sine of the arc; or, it is the same in magnitude as the sine of the complement of the arc.
5. The Tangent of an arc is a line touching the circle in one extremity of the arc, and continued from thence, to meet a line drawn through the center and the other extremity.
6. The Cotangent of an arc is the tangent of the complement of the arc. The Co is but a contraction of the word complement.
7. The Secant of an arc is a line drawn from the center of the circle to the extremity of the tangent.
8. The Cosecant of an arc is the secant of the complement.
9. The Versed Sine of an arc is the distance from the extremity of the arc to the foot of the sine.
For the sake of brevity, these technical terms are contracted thus: for sine A B, we write sin. A B; for cosine A B, we write cos. A B; for tangent A B, we write tan. A B, etc.