16.2 (n- 1)/2 (the length of the new delta side is 2 1/2 times that of the previous delta side).
17.AB⊥BC
18.② (① there are obvious errors, ③ only point P is required to be on the straight line of AB trisection).
A. What do you usually do when you study Japanese?
In fact, after learning Japanese, there are still many future employment directions. Japanese teacher, Jap