Solution -
drawing a perpendicular from AQ to TS, we get a right angle triangle AQT
Using Pythagoras Theorem,
AT² = AQ² + QT²
⇒26² = 24² + QT² (∵ Due to symmetry AQ = RS)
⇒QT² = 676-576 = 100
⇒QT = 10
As TS = QT + QS = 12 + 10 = 22 ( ∵ Due to symmetry AR = QS )
∴ TS = 22 (ans)