Question

what is ( mangle u )?
( mangle u = square^circ )

Explanation:

Step1: Identify right angle

Since $UT$ is a diameter, $\angle S = 90^\circ$ (angle inscribed in semicircle).

Step2: Sum of triangle angles

The sum of angles in $\triangle STU$ is $180^\circ$.
$m\angle U + m\angle T + m\angle S = 180^\circ$

Step3: Solve for $m\angle U$

Substitute known values:
$m\angle U + 57^\circ + 90^\circ = 180^\circ$
$m\angle U = 180^\circ - 90^\circ - 57^\circ$
$m\angle U = 33^\circ$

Answer:

$33$