PQRS is a diamete

Given,

Radius (OS) of the circle = 6 cm

Diameter (PS) of the circle = 12 cm

PQ, QR, and RS, three parts of the diameter are equal

So,

PQ = QR = RS = 4 cm

And

QS = 2 × 4 = 8 cm

So, Required perimeter;

= arc PS + arc QS + arc PQ

= π ×6 + π×4 + π×2

37.7 cm