Convert the angle ANGLE.deg° to radians.

ANGLE.deg / 180 * PI radians

There are 360 degrees in a circle. There are also 2\pi radians in a circle.

In other words, there are \pi radians per 180 degrees. So we can convert from degrees to radians by multiplying by \pi, and dividing by 180^\circ.

ANGLE.deg^\circ \times \dfrac{\pi}{180^\circ}

\displaystyle = ANGLE.rad radians