y=x^2,
the curve is symmetrical about
the +ve y axis thro the origin
rotate 90 deg AC;
the curve is symmetrical about
the -ve x axis thro the origin
rotate by a further 180 deg AC;
the curve is symmetrical about
the +ve x axis thro the origin
reflect in the line y=x;
this is the image of the +ve x
axis,therefore we are back to
where we started
that is,
y=x^2,the vertex being at {0,0},
the curve goes thro the origin
and is symmetrical about the +ve
y axis