State True or False.
The parallelogram circumscribing a circle is a rhombus.
5cm
A parallelogram ABCD circumscribes a circle with centre O.
We know that the lengths of tangents drawn from an exterior point to a circle are equal.
∴ AP = AS, . . . (i) [tangents from A]
BP = BQ, . . . (ii) [tangents from B]
CR = CQ, . . . (iii) [tangents from C]
DR = DS . . . (iv) [tangents from D]
Adding (i), (ii), (iii) and (iv), we get,
AP + BP + CR + DR = AS + DS + BQ + CQ
AB + CD = AD + BC . . . (v)
But we know that in a parallelogram opposite sides are equal.
∴ AD = BC and AB = CD, putting these in (v) we get
2 AB = 2 AD
AB = AD = CD = BC.
Hence, ABCD is a rhombus.