Answer:
71 degrees
Explanation
From the triangle shown;
YX² = YZ² + XZ² - 2(YZ)(XZ) cos Z
28² = 25² + 23² - 2(25)(23) cos Z
784 = 625 + 529- 1150 cos Z
784 - 1154 = -1150cos Z
-370 = -1150cos Z
cos Z = 370/1150
cos Z = 37/115
cos Z = 0.3217
Z = arccos 0.3217
Z = 71.23
hence the measure of <Z is 71 degrees