In a ∆PQR, ∠Q : ∠R = 6 : 5 and I and O are the incentre and orthocentre of ∆PQR whereas I1 is the incentre of ∆QIR. If ∠QI1R = 147°, then what is the ratio of the measure of ∠POR to the measure of ∠PIQ?
In a ∆PQR, ∠Q : ∠R = 6 : 5 and I and O are the incentre and orthocentre of ∆PQR whereas I1 is the incentre of ∆QIR. If ∠QI1R = 147°, then what is the ratio of the measure of ∠POR to the measure of ∠PIQ? Correct Answer 9 : 10
Given:
∠Q : ∠R = 6 : 5 and ∠QI1R = 147°
Calculation:
∠QI1R = 90° + (∠QIR/2)
⇒ 147° = 90° + (∠QIR/2)
⇒ ∠QIR = 114°
∠QIR = 90° + (∠P/2)
⇒ 114 ° = 90° + (∠P/2)
⇒ ∠P = 48°
Suppose, ∠Q = 6x and ∠R = 5x.
⇒ 48° + 6x + 5x = 180°
⇒ 11x = 132°
⇒ x = 12
∠Q = 6x = 72°
∠R = 5x = 60°
∠POR = 180° – ∠Q
⇒ ∠POR = 180° – 72° = 108°
∠PIQ = 90° + (∠R/2)
⇒ ∠PIQ = 90° + 30° = 120°
∴ Required ratio = 108 : 120
= 9 : 10
মোঃ আরিফুল ইসলাম
Feb 20, 2025