Point Z is equidistant from the vertices of ΔTUV.
Which must be true?
TA=TB
AZ=BZ
BTZ=BUZ
TZA= TZB

Consider right triangles BTZ and BUZ.
ZB = ZB (Common)
ZT = ZU (Given)
Therefore, ΔBTZ ≅ ΔBUZ (By RHS theorem)
Hence, by CPCTC,
∠BTZ = ∠BUZ
Answer:
(C)
Step-by-step explanation:
It is given that Point Z is equidistant from the vertices of ΔTUV, therefore ZT=ZU=ZV.
Now, from ΔBTZ and ΔBUZ, we have
ZT=ZU (Given)
BZ=ZB (common)
therefore, by RHS rule of congruency,
ΔBTZ≅ΔBUZ
Thus, by corresponding parts of congruent triangles, we have
∠BTZ=∠BUZ
Thus, option C is correct.
Also, it is not necessary that TA=TB and AZ=BZ because there is no information given regarding these equalities.