Function circles_tangent_to_three 

pub fn circles_tangent_to_three(
    targets: &[Target2; 3],
    tol: Tolerances,
) -> OgeomResult<Vec<TangentCircle>>

Circles tangent to all three targets: the Apollonius family and its degenerate relatives, every candidate verified against the literal tangency distances before it is returned.

Errors

OgeomError::Construction if two targets coincide, which asks a different, underdetermined question.