Formula for semi circle with diameter up? So I know the formula for a semi circle is
$$y = \sqrt{r^2 - x^2}$$
However, what if I wanted to find the equation for a semi circle who's diameter is at the top of the graph?
Would this be the best solution?
$$y = r-\sqrt{r^2 - x^2}$$
Thanks

The $r$ at the start is optional.  It just shifts the semicircle up so the bottom is tangent to the $x$ axis.  If you delete it the semicircle is below the $x$ axis.  In both cases it has the orientation you desire.  Good work.
