The ANGLE BISECTOR mentioned in the problem is simply just a line that separates an angle in half.
Meaning if it bisects ∠SUT which is 34. It just means that it divides the angle 34 into 2 equal parts.
Therefore ∠1 is just one-half of the ∠SUT.
[tex]\begin{gathered} m\angle1=\frac{\angle SUT}{2} \\ m\angle1=\frac{34}{2} \\ m\angle1=17 \end{gathered}[/tex]
Therefore the measurement of ∠1 is 17°.
