ANGLE BISECTORS / INCENTER
These are the ANGLE BISECTORS of a triangle.
Their point of concurrency is the INCENTER.
Notice that the INCENTER is equidistant to the SIDES of the triangle.
Drag the vertices of the triangle around, and notice that the INCENTER is ALWAYS equidistant to the SIDES of the triangle.
An interesting thing happens when the triangle is equilateral. See if you can find out what it is!