Definition of Trigonometry

Let us understand what is Trignometry,
Definition of Trigonometry: 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. Incidentally trigonometry considers also certain time-saving aids in computation such as logarithms, which are generally employed in the solution of triangles. Briefly stated,

Trigonometry is 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.

Before we get into the basic definitions of Trigonometric Functions, let us look at the basic definition of a function.
Hope the above explanation helped you..