Viviani Theorem

[fasibasar]

What is the proof of the following theorem? I need help.
http://www.gogeometry.com/problem/p222_viviani_theorem_equilateral_triangle_exterior.htm

 

[mmm4444bot]

Check out THIS SITE.

If your web browser has sufficient JAVA, you can click-and-drag point P outside the triangle, to see what happens. They describe one proof method.

 

[fasibasar]

I know this solution. But in my question the point is outside the triangle.

 

[mmm4444bot]

you can click-and-drag point P outside the triangle