In the given figure, PQR is an equilateral triangle and QRST is a square. Then ∠PSR is

In the given figure, PQR is an equilateral triangle and QRST is a square. Then ∠PSR is

Correct option is B)

QRST is a square
let side=a

PQ=PR=QR=a
∠PRQ=60∘(△PQR is equilateral )

In △PRS
PR=PS
∠PSR=∠SPR
(angle opp. to equal sides are also equal)
              =x

∠PRS=60+90=150∘
x+x+150=180( sum of angle of △PRS)
2x=30∘
x=15∘