Math, Mathematics, Geometry, Path, 2d.
CB. Then we draw a line perpendicular to AB, as seen in figure 4. Figure 4 According to the Pythagorean Theorem, a is always less than c, and b is always less than d. We already have AB = a+b and AC+CB = c+d. Since a<c and b<d, we have a+b < c+d, which is the same as AB < AC + CB. In other words,