As shown in the figure, it is known that point a is a point in the acute angle ∠ mon. Try to determine point B and point C on OM and on respectively, so as to minimize the perimeter of △ ABC. Explain the reason

As shown in the figure, it is known that point a is a point in the acute angle ∠ mon. Try to determine point B and point C on OM and on respectively, so as to minimize the perimeter of △ ABC. Explain the reason

Make a symmetric point A1, A2 about OM, on
The intersection of A1A2, OM and on is B, c!
AB+BC+AC=A1B+BC+A2C
The shortest line segment between two points shows that when A1, B, C and A2 are collinear, the perimeter is the smallest!