Consider

with acute angle

. Thorugh a point

perpendiculars are drawn to

and

, the feet of which are

and

respectively. The point of intersection of the altitudes of

is

. What is the locus of

if

is permitted to range over
a) the side

;
b) the interior of

.
%V0
Consider $\triangle OAB$ with acute angle $AOB$. Thorugh a point $M \neq O$ perpendiculars are drawn to $OA$ and $OB$, the feet of which are $P$ and $Q$ respectively. The point of intersection of the altitudes of $\triangle OPQ$ is $H$. What is the locus of $H$ if $M$ is permitted to range over
a) the side $AB$;
b) the interior of $\triangle OAB$.