In a ∆PQR, I is incentre and O is the orthocenter, ∠QIR : ∠QOR is 61 : 58. ∠Q is 44° more than ∠R and X is the external angle bisector of ∠P and ∠R, then what is the ratio of ∠PXR to ∠PCQ where C is the circum-center of ∆PQR?
In a ∆PQR, I is incentre and O is the orthocenter, ∠QIR : ∠QOR is 61 : 58. ∠Q is 44° more than ∠R and X is the external angle bisector of ∠P and ∠R, then what is the ratio of ∠PXR to ∠PCQ where C is the circum-center of ∆PQR? Correct Answer 25 : 36
Give:
∠QIR : ∠QOR = 61 : 58
Calculation :
Let ∠QIR and ∠QOR be ‘61x’ and ‘58x’ respectively.
∠QIR = 90° + (∠P/2)
⇒ 122x = 180° + ∠P ----(i)
∠QOR = 180° – ∠P
⇒ 58x = 180° – ∠P ----(ii)
From (i) and (ii), we get
x = 2 and ∠P = 64°
now, 64° + ∠Q + ∠Q – 44° = 180°
⇒ ∠Q = 80°
⇒ ∠R = 80° - 44° = 36°
∠PCQ = 2 × ∠R = 72°
∠PXR = 90° – (∠Q/2) = 90° – 40° = 50°
∴ Required ratio = 50 : 72
= 25 : 36
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Feb 20, 2025