(D) quadrilateral whose opposite angles are supplementary
Explanation:
We know that,
Sum of all angles of a quadrilateral = 360°
⇒ ∠A + ∠B + ∠C + ∠D = 360°
Dividing LHS and RHS by 2,
⇒ ½ (∠A + ∠B + ∠C + ∠D) = ½ × 360° = 180°
Since, AP, PB, RC and RD are bisectors of ∠A, ∠B, ∠C and ∠D
⇒ ∠PAB + ∠ABB + ∠RCD + ∠RDC = 180° … (1)
We also know that,
Sum of all angles of a triangle = 180°
∠PAB + ∠APB + ∠ABP = 180°
⇒ ∠PAB + ∠ABP = 180° – ∠APB …(2)
Similarly,
∴ ∠RDC + ∠RCD + ∠CRD = 180°
⇒ ∠RDC + ∠RCD = 180° – ∠CRD …(3)
Substituting the value of equations (2) and (3) in equation (1),
180° – ∠APB + 180° – ∠CRD = 180°
⇒ 360° – ∠APB – ∠CRD = 180°
⇒ ∠APB + ∠CRD = 360° – 180°
⇒ ∠APB + ∠CRD = 180° …(4)
Now,
∠SPQ = ∠APB [vertically opposite angles]
∠SRQ = ∠DRC [vertically opposite angles]
Substituting in equation (4),
⇒ ∠SPQ + ∠SRQ = 180°
Hence, PQRS is a quadrilateral whose opposite angles are supplementary.
Therefore, option (D) is the correct answer.