ABCD is a trapezium in which AB//DC, O is midpoint of BC. Through the point O a line PQ//DA has been drawn which intersects AB at Q and DC produced at P. Prove that ar(ABCD) = ar(AQPD)
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Answer:
Step-by-step explanation:
O is the midpoint of BC.
Implies, BO = CO = 1/2 BC -(1)
DP // AB and BC is the transversal.
Implies, ∠PCO = ∠QBO (Alternate Interior Angles) -(2)
∠COP = ∠BOQ (Vertically Opposite Angles) -(3)
From (1), (2) and (3)
ΔCOP ≅ ΔBOQ (By ASA rule)
Implies, ar(ΔCOP) = ar(ΔBOQ) -(4)
ar(ABCD) = ar(ADCOQ) + ar(BOQ)
= ar(ADCOQ) + ar(COP) [from 4]
∴ ar(ABCD) = ar(AQPD)
Hence, proved.
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: In trapezium ABCD, AB || DC and L is mid point of BC. Through L, a line PQ || AD has been drawn which meets AB in P and DC produced in Q. Prove that ar(ABCD) = ar(APQD)
: AB || CD and PQ || AD where L is mid point on BC.
: ar(ABCD) = ar(APQD)
: When AB || CD Or QD || AP and PQ || AD then APQD is a parallelogram.
In ∆CLQ and ∆PLB we have,
∠LCQ = ∠LBP [ Alternate angles ]
LC = LB [ L is mid point on BC ]
∠CLQ = ∠PLB [ Vertically opposite angles ]
Hence ∆CLQ and ∆PLB are congruent by ASA congruency.
Therefore, ar(∆CLQ) = ar(∆PLB)
Adding ar(ADCLP) both sides we get,
ar(ADCLP) + ar(∆CLQ) = ar(∆PLB) + ar(ADCLP)
ar(APQD) = ar(ABCD)
: AB || CD and PQ || AD where L is mid point on BC.
: ar(ABCD) = ar(APQD)
: When AB || CD Or QD || AP and PQ || AD then APQD is a parallelogram.
In ∆CLQ and ∆PLB we have,
∠LCQ = ∠LBP [ Alternate angles ]
LC = LB [ L is mid point on BC ]
∠CLQ = ∠PLB [ Vertically opposite angles ]
Hence ∆CLQ and ∆PLB are congruent by ASA congruency.
Therefore, ar(∆CLQ) = ar(∆PLB)
Adding ar(ADCLP) both sides we get,
ar(ADCLP) + ar(∆CLQ) = ar(∆PLB) + ar(ADCLP)
ar(APQD) = ar(ABCD)
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