The perimeter of the parallelogram is 56 cm. Find the sides of the parallelogram if the sum of its two sides is 20 cm.

Given:
ABCE – parallelogram,
AB + CE = 20 centimeters,
the ABCE perimeter is 56 centimeters.
Find the lengths of the sides of the parallelogram ABCE: AB, CE, BC, AE -?
Decision:
Consider a parallelogram ABCE. Its opposite sides are equal to each other, then BC = AE, AB = CE.
Therefore AB = CE = 20: 2;
AB = CE = 10 centimeters;
R ABCE = AB + BC + CE + AE;
P ABCE = 10 + BC + 10 + AE;
56 = 20 + BC + AE;
BC = AE = (56 – 20): 2;
BC = AE = 16: 2;
BC = AE = 8 centimeters.
Answer: 10 centimeters; 10 centimeters; 8 centimeters; 8 centimeters.