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See the problem
Isosceles.

The triangle OPA has a vertex O at the origin and OA along
the *x* axis, such that P has coordinates *(x, y)*
and A has coordinates *(2x, 0)*. By moving the position
of the point P infinitely many isosceles triangles can be
formed all having an area of 12 square units. What is the
locus of P such that the area of the triangle OPA is 12
square units? In the Java applet below, the point P is
controlled by sliding the red point along the red line. If
the red point disappears from view, simply press reload.