Answer: The length of CK = 3 units.
Step-by-step explanation:
Given parallelogram ROCK and KR = 57 units , RO = 3 units
A parallelogram is a kind of quadrilateral with following characteristics:
So , if ROCK is a parallelogram, then
RO = CK [Opposite sides are congruent]
i..e CK = RO= 3 units
That means , the length of CK = 3 units.