Triangle with a maximum area

The applet allows to investigate the task: Finding the maximum area of a triangle of all triangles have the same perimeter. When the vertex A is dragged, the location of vertex C changes automatically, in accordance with the perimeter defined by the slide bar. During each stage, the following values appear on the screen: The perimeter of the triangle P, the area of the triangle, the magnitudes of the angles by the vertices B and C. When the vertex A is dragged, one can see that the maximum area is obtained for an equilateral triangle.