Mathematics
In the given figure, ABCD is a trapezium with DC//AB, ∠AOB = 126° and ∠DCQ = ∠CDP = 52°.
Find the values of x and y.

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Answer

Given: ABCD is a trapezium with DC//AB, ∠AOB = 126° and ∠DCQ = ∠CDP = 52°.
To find: The values of x and y.
Construction: Extend P and Q such that they meet at R.
In Δ RDC,
⇒ ∠RDC = ∠RCD = 52° (since DCQ = CDP = 52°) ……………….(1)
Since the base angles are equal, Δ RDC is isosceles, which means:
⇒ DR = CR.
In quadrilateral ABCD, since AB ∥ DC, we use the property of corresponding angles:
⇒ ∠RAB = ∠RDC = 52° ( Corresponding angles) ………………..(2)
⇒ ∠RBA = ∠RCD = 52° ( Corresponding angles) ………………..(3)
Since ∠RAB = ∠RBA, we conclude that:
⇒ AR = RB
From the figure, we also note:
AD = AR - DR = RB - CR = BC
Therefore, we can say that ABCD is an isosceles trapezium.
Since, OA = OB, we conclude that:
⇒ ∠OAB = ∠OBA
Using the angle sum property in Δ AOB:
⇒ ∠OAB + ∠OBA + ∠AOB = 180°
⇒ ∠OAB + ∠OAB + 126° = 180°
⇒ 2∠OAB + 126° = 180°
⇒ 2∠OAB = 180° - 126°
⇒ 2∠OAB = 54°
⇒ ∠OAB = = 27°
Now, ∠x = ∠DAB - ∠OAB = 52° - 27° = 25°
Using angle sum property in Δ ABC:
∠ABC + ∠BAC + ∠ACB = 180°
⇒ 52° + 27° + y = 180°
⇒ 79° + y = 180°
⇒ y = 180° - 79° = 101°
Hence, the value of x = 25° and y = 101°.
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