What is the arctangent of 0 ?
arctan 0 = ?
The arctangent is the inverse tangent function.
Since
tan 0 = tan 0º = 0
The arctangent of 0 is equal to the inverse tangent function of 0, which is equal to 0 radians or 0 degrees:
arctan 0 = tan-1 0 = 0 rad = 0º