12. In quadrilateral ABCD, AC = BD and AC I BD.
If P, Q, R and S are the midpoints of the
sides AB, BC, CD and DA respectively, prove
that PQRS is a square.
Answers
Step-by-step explanation:
Solution :
Given In a quadrilateral ABCD, P, Q, R and S are the mid-points of sides AB, BC, CD and DA, respectively. Also, AC = BD
To prove PQRS is a rhombus.
Proof In ΔADC, S and R are the mid-points of AD and DC respectively. Then, by mid-point theorem.
" "SR||AC and SR=(1)/(2)AC" "...(i)
In DeltaABC, P and Q are t he mid-points of AB and BC respectively. Then, by mid-point theorem
" "PQ||AC and PQ=(1)/(2)AC" "...(ii)
From Eqs. (i) and (ii), " "SR=PQ=(1)/(2)AC" "...(iii)
Similarly, in DeltaBCD, " "RQ||BD and RQ=(1)/(2)BD" "...(iv)
And in DeltaBAD, " "SP||BD and SP=(1)/(2)BD" "...(v)
From Eqs. (iv) and (v), " "SP=RQ=(1)/(2)BD=(1)/(2) AC" " [given, AC=BD]...(vi)
From Eqs. (iii) and (vi), " "SR=PQ=SP=RQ
It shows that all sides of a quadrilateral PQRS are equal.
Hence, PQRS is a rhombus. " " Hence proved.
Answer:
sorry dear it is hard to do....