This applet shows the construction of the incenter of a triangle.

Move points A, B and C and notice what happens to the triangle.
Answer the following questions:
a. What are the blue lines in the construction called?
b. How are those blue lines constructed?
c. What is point D called?
d. Constructing a circle inside triangle ABC is called what?
e. In what special way do the radii of the circle intersect the sides of the triangle?
f. What type of triangle is constructed when the radii overlap the bluelines?
g. What is unique about the blue lines when all three sides of the triangle are congruent?