# Trigonometry Triangle to Show Sine, Cosine, and Tangent

## Description

Right triangle OCA, inside of Circle O is used to show that side AC is "opposite" O and side OC is "adjacent" to O. OA is the hypotenuse. Sine is defined as the ratio of the opposite side to the hypotenuse (AC/OA). Cosine is defined as the ratio of the adjacent side to the hypotenuse (OC/OA), and Tangent is defined as the ratio of the opposite side to the adjacent side (DB/OB).

## Keywords

angle, angles, cosine, Sine, tangent, triangle, trigonometric circle, trigonometry

## Galleries

## Source:

International Correspondence Schools *I.C.S. Reference Library Mathematics* (Scranton: International Textbook Company, 1905) Geometry & Trigonometry Pg. 25

Courtesy the private collection of Roy Winkelman