Answer 3

One possible answer is:

Coordinate
`-`x:Real `-`y:Real
`+`create( in xp:Real = 0.0, in yp:Real = 0.0 ):Coordinate `+`create( in coord:Coordinate ):Coordinate `+`getX():Real `+`getY():Real `+`setX( in xp:Real ) `+`setY( in xp:Real ) `+`length():Real `+`angle():Real `+`distance( in coord:Coordinate ):Real `+`transform( in T:Transformation )