in the adjoining figure, ABCD is a trapezium, if AOB = 126
and PDC = QCD = 52°, then find x & y.
(A) x = 52°, y = 52°
(C) x = 101° y = 25°
(B) x = 25y = 101°
(D) x = 52, y = 101°
Answers
Solution :-
Construction :- Produce AP and BQ to meet at R.
In ∆RDC we have,
→ ∠RDC = ∠RCD (given 52°) ---------- Eqn.(1)
so,
→ DR = CR (sides opposite to equal angles are equal in length.)
now,
→ ∠RAB = ∠RDC (given that, ABCD is a trapezium. so, AB || DC , therefore, corresponding angles are equal). -------- Eqn.(2)
Similarly,
→ ∠RBA = ∠RCD (corresponding angles .) -------- Eqn.(3)
from Eqn.(1) , Eqn.(2) and Eqn.(3) we can conclude that,
→ ∠RAB = ∠RBA
or,
→ AR = RB .
then,
→ AD = AR - DR = RB - CR = BC
therefore, we can conclude that, ABCD is an isosceles trapezium.
hence,
→ OA = OB
→ ∠OAB = ∠OBA.
now, in ∆AOB we have,
→ ∠OAB + ∠OBA + ∠AOB = 180° (By angle sum property.)
→ 2∠OAB + 126° = 180°
→ 2∠OAB = 180° - 126°
→ 2∠OAB = 54°
→ ∠OAB = 27°
therefore,
→ ∠x = ∠DAB - ∠OAB
→ ∠x = 52° - 27°
→ ∠x = 25° (Ans.)
also, in ∆ABC, we have,
→ ∠ACB + ∠CAB + ∠ABC = 180° (By angle sum property.)
→ y + 27° + 52° = 180°
→ y = 180° - 27° - 52°
→ y = 180° - 79°
→ y = 101° (Ans.)
Learn more :-
In ABC, AD is angle bisector,
angle BAC = 111 and AB+BD=AC find the value of angle ACB=?
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