Angle notation or phasor notation is a notation used in electronics.   can represent either the vector    or the complex number

Complex number

A complex number is a number consisting of a real part and an imaginary part. Complex numbers extend the idea of the one-dimensional number line to the two-dimensional complex plane by using the number line for the real part and adding a vertical axis to plot the imaginary part...

    both of which have magnitudes of 1.  A vector whose polar coordinates are magnitude    and angle    is written      For converting between polar and rectangular forms, see Converting between polar and Cartesian coordinates.
In electronics

Electronics

Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...

 and electrical engineering

Electrical engineering

Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...

, there may also be an implied conversion from degrees to radians. For example    would be assumed to be    which is the vector    or the number