ABCD a rectangle and P, Q, R and S are mid points of the sides AB, BC,
CD and DA, respectively. Show that the quadrilateral PQRS is a rhombus
Answers
Given: ABCD is a rectangle
P, Q, R, S are the mid points of ABCD
To prove: PQRS is a rhombus ( parallelogram and adjacent sides)
Construction: Join AC
Proof:
In triangle ADC,
S is the mid point of AD
R is the mid point of DC
Therefore, SR || AC and SR = 1/2 AC »»» Eq 1
(by midpoint theorem)
In triangle ABC,
P is the mid point of AB
Q is the mid point of BC
Therefore, PQ || AC and PQ = 1/2 AC »»» Eq 2
(by midpoint theorem)
From Eq 1 and Eq 2
SR || PQ, SR=PQ
therefore, PQRS is a parallelogram (a pair of oppo sides equal)
In triangle SAP and in triangle QBP
SA=QB ( oppo sides of a rectangle are equal
1/2 AD =1/2 BC )
<A = <B = 90 degree ( angles of rectangle are 90 degree)
AP = BP ( P is the midpoint )
therefore, triangle SAP =~ triangle QBP ( SAS rule )
PS =PQ ( cpct )
therefore, PQRS is a rhombus [ a parallelogram with a pair of adjacent sides equal]
Hope it heps you !!!!