We first solve for angle TZU which is determined by the formula:
mTZU = 0.5(arcTU + arcSR)
mTZU = 0.5(72°+100°) = 86°
By vertical angle, mTZU = mSZR = 86°
We note that the sum of all angles formed is 360°. Solving for the remaining angles:
360° - 86° - 86° = 188°
Since mSZT is equal to mRZU by vertical angle, we divide 188° by 2.
188°/2 = 94°
m∠SZT = 94°