In the given figure, OQ = QR = RT and O is the centre of the circle. What is ∠PTQ ?

OP = OQ = QR = RT = r

Ιn Δ OQR,

OQ = QR = OR

∴ ∠RQO = 60°

⇒ ∠PSR = 180° – 60° = 120

∴ ∠TSR = 180° – 120° = 60°

In ΔPQT,

PQ = QT

∴ ∠QTP = ∠QPT = 60°