Draw a circle with center O with radius 7cm. Draw any one of the diameters AB. With same center O, draw another circle with radius 4cm. Draw any one of the diameters CD for this circle too. If you join the ends of both the diameters, the figure you will get is:
Parallelogram
Draw the circles and the diameters. You will get:
If you mark the diameter of smaller circle as AB and larger circle as CD, after joining them you will get:
Fig. ABCD is a parallelogram. When AB is perpendicular to CD, ABCD becomes a rhombus.