a. From the figure,
S ↔ X, T ↔ Z, U ↔ Y i.e.,
STU ↔ XZY, or SUT ↔ XYZ, or
TUS ↔ ZYX, or TSU ↔ ZXY, or
UTS ↔ YZX, or UST ↔ YXZ
∴ ∆STU \(\cong\) ∆XZY, or ∆SUT \(\cong\) ∆XYZ, or
∆TUS \(\cong\) ∆ZYX, or ∆TSU \(\cong\) ∆ZXY, or
∆UTS \(\cong\) ∆YZX, or ∆UST \(\cong\) ∆YXZ
b. If ∆XYZ \(\cong\) ∆STU, then
∠Y \(\cong\) ∠T, ∠Z \(\cong\) ∠U,
seg XY \(\cong\) seg ST, seg XZ \(\cong\) seg SU
∴ But, all the above statements are wrong. The statement AXYZ \(\cong\) ASTU is wrong.