UPSC 2017 CDS II Math Paper

∠PQR = 90°
Remember: Radius is perpendicular to the tangent at the point of contact.
In ΔPQR,
PQ = QR = r
⇒ ∠QRp = ∠QPR = 45°
Remember: Equal sides have equal angles opposite to them.
Area of the part of the triangle which is outside the circular region
= Area of the ΔPQR – Area of the sector PQRP