Problem while applying trigonometric functions in QGIS 3.1

Question

Using the Trigonomteric functions in the QGIS 3.1 field calculator gives me unexpected output. For example sin(180) produces the output -0.8011526357338304 instead 0.

What is the reason for this?

How do I achieve expected result using degree as input?

Answer 1

Trigonometric functions in QGIS expressions (sin, cos, tan) expect the input angle to be specified in radians.

You can convert your input to radians using the radians function, so your example would look like this:

sin(radians(180))