Whichever segment it is to which you are referring, it does not need to be red; it can be any color.
The segment that intersects both foci is called the semi-major axis. The segment that is perpendicular to the semi-major axis with one end midway between the foci is called the semi-minor axis.
radius
24
26
21
4 11 10.8
radius
24
10
26
21
12
24
8
To determine the length of the blue line segment, we need to understand the context of the transverse axis and the red line segment. If the red line segment represents the length of the major axis of an ellipse, and the transverse axis is the distance across the ellipse at its widest point, then the blue line segment could be half the length of the transverse axis. However, without additional information about the relationship between these segments, a precise length for the blue line segment cannot be determined.
4 not 9..... ANSWER FOR APEX 10 (:
4 11 10.8
The length of the major axis of an ellipse is determined by the lengths of its semi-major and semi-minor axes. In this case, if the red line segment represents the semi-major axis (8), the length of the major axis would be twice that, which is 16. The blue line segment, being shorter (4), represents the semi-minor axis. Thus, the major axis of the ellipse is 16 units long.