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\(ABCD\) is a parallelogram where \(P\) and \(Q\) are mid-points of opposite sides of \(AB\) and \(CD\). If \(AQ\) intersects \(DP\) at \(S\) and \(BQ\) intersects \(CP\) at \(R\), then prove that \(DPBQ\) is a parallelogram.
 
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S. No.
Statement
Reason
1.
\(PB \ || \ DQ\)
Since 
2.
 \(P\) is the mid-point of \(AB\)
 
\(Q\) is the mid-point of \(CD\)
3.
\(AB = CD\)
4.
 Half of the equal lines are equal.
5.
 Using (2)
6.
\(DPBQ\) is a parallelogram
 
Hence, proved.
Answer variants:
\(AB \ || \ CD\)
Opposite sides of a parallelogram are equal
12AB=12CD
12AD=12BC
A quadrilateral is a parallelogram,
if a pair of opposite sides is equal and parallel
\(AB = \frac{1}{2} AB\) and \(DQ = \frac{1}{2} CD\)
\(PB \ || \ DQ\)
PB=DQ
\(PB = \frac{1}{2} AB\) and \(DQ = \frac{1}{2} CD\)
A quadrilateral is a parallelogram,
if a pair of opposite sides is equal and perpendicular
\(AD \ || \ CB\)
All the sides of a parallelogram are equal