Trigonometry considers the properties of angles and certain ratios associated with angles, and applies the knowledge of these properties to the solution of triangles and various other algebraic and geometric problems. It also considers a certain time-saving aids in computation such as logarithms, which are generally used in the solution of triangles.
Trigonometry is basically the science of angular magnitudes and the art of applying the principles of this science to the solution of problems.
The word Trigonometry comes from two Greek words, trigonon = triangle, and metron = measure. The method was originated in the second century B.C. by Hipparchus and other early Greek astronomers in their attempts to solve certain spherical triangles. The term trigonometry was not used until the close of the sixteenth century.