If you want parabolas that illustrate specific equations, then use the Excel
graphing route. If you can deal with rough parabola, then there are three
autoshapes, basic shapes, that can be used to draw rough parabolas.
Arc, Blocked Arc & moon.
Use the adjustment handles (yellow diamonds and white bubles) to shape the
parabola arc and size.
The blocked arc and moon can provide a limited fill capability if you want
to shade under the figure.
Since many parabolic figures in geometry begin on an X axis, if you want a
flat bottom arch, you will need to overlay a figure (rectangle) in front of
the parabola. Set the rectangle's border and fill properties to no fill/no
line or match the colors to your background. Voila, a flat bottom parabola.
