Point in sagittal plane

Hi can anyone please tell me how to find whether a 3d point is in sagittal plane or not ?

Thanks

[Ivan van der Kroon]

what is your coordinate system? if it is normal defined Cartesian it are all points for which y=0;

Answer 1

[Sean de Wolski]

Of course it's in a sagittal plane. It's also in a transverse and coronal plane.