Khan Academy Static

This tutorial experiments with lines that divide the angles of a triangle in two (angle bisectors). As we'll prove, all three angle bisectors actually intersect at one point called the incenter (amazing!). We'll also prove that this incenter is equidistant from the sides of the triangle (even more amazing!). This allows us to create a circle centered at the incenter that is tangent to the sides of the triangle (not surprisingly called the "incircle").

3752_Inradius_perimeter_area.html

3751_Incenter_and_incircles_of_a_triangle.html

3750_Distance_between_a_point_line.html