T/3+9=12 ?? no clue how to do

The line containing the midpoints of the legs of right triangle abc where a(-5,5), b(1, 1), and c(3, 4) are the vertices.

Which undefined geometric term is described as a location on a coordinate plane that is designed by an ordered pair (x, y) ?

If chord ab is congruent to chord cd, then what must be true about ef and eg?