Trigonometry in Greek language means triangle measurment. As a science it was widely used in the second century B.C. by Hypparchus a greek astronomer and Rhodes another mathematician in various computation involving sides and angles of triangle. After the development of complex numbers the great contributions of De Moivre, Euler and Cauchy made trigonometry a study far from that limited to angles and triangle. It is now an essential branch of mathematical analysis. | |||
Angles | |||
An angle can be defined as a measure of rotation of a ray about its vertex. | |||
Note 1: | An angle is said to be positive if it is traced out by the ray in the anti clockwise direction. |
||
Note 2: | An angle is said to be negative if it is traced out by the ray in the clockwise direction. |
||
Degree measure | |||
If a rotation from the initial side to the terminal side is (1/360) th of a complete revolution, the angle is said to be one degree. It is written as 1°. | |||
Note 1: | One degree is divided into 60 equal parts called minutes. (denoted by 60I) |
||
Note 2: | One minute is divided into 60 seconds (denoted by 60’’) | ||
Back | Next |