In parallelogram ABCD, two points P and Q are taken on diagonal BD such that DP = BQ (see Fig. 8.20). Show that:
(i) Δ APD ≅Δ CQB
(ii) AP = CQ
(iii) Δ AQB ≅Δ CPD
(iv) AQ = CP
(v) APCQ is a parallelogram
(i) In ΔAPD and ΔCQB,
∠ADP = ∠CBQ (Alternate interior angles for BC || AD)
AD = CB (Opposite sides of parallelogram ABCD)
DP = BQ (Given)
ΔAPD ΔCQB (Using SAS congruence rule)
(ii) As we had observed that,
ΔAPD ΔCQB
AP = CQ (CPCT)
(iii) In ΔAQB and ΔCPD,
∠ABQ = ∠CDP (Alternate interior angles for AB || CD)
AB = CD (Opposite sides of parallelogram ABCD)
BQ = DP (Given)
ΔAQB ΔCPD (Using SAS congruence rule)
(iv) As we had observed that,
ΔAQB ΔCPD,
AQ = CP (CPCT)
(v) From the result obtained in (ii) and (iv),
AQ = CP and AP = CQ
Since,
Opposite sides in quadrilateral APCQ are equal to each other,
APCQ is a parallelogram