1. When angle α=0˚, it is called a zero angle.
2. When angle is between 0˚<α<90˚, it is called an acute angle.
3. When angle is α=90˚, it is called a right angle.
4. When angle is between 90˚<α<180˚, it is called an obtuse angle.
5. When angle is α=180˚, it is called a straight angle.
6. When angle is in between 180˚<α<360˚, it is called a reflex angle.
7. When angle is α=360˚, it is called a complete angle.
