Using diagonal properties, construct a rhombus whose diagonals are of lengths \(7.8\ cm\) and \(6 \ cm\).
Construction:

Step 1:
Step 2:
Step 3:
Step 4:
Thus, \(LUCK\) is the required parallelogram.
Answer variants:
Draw a line segment of length \(LC = 7.8 \ cm\).
Mark a point \(O\) of line segment \(LC\) such that \(LO = OC = 3.9 \ cm\). At point \(O\), draw a perpendicular bisector using a protractor.
With \(O\) as centre and \(3 \ cm\) as radius, draw two arcs on the perpendicular line and mark the intersections as \(U\) and \(K\), respectively.
Join \(LU\), \(UC\), \(CK\) and \(KL\).