The perimeter of parallelogram ABCD is 50 cm, side AB is 10 cm. Find the sides of the parallelogram.

In order to answer the question of the problem, namely to find the sides of the parallelogram, we will recall the formula for finding the perimeter of the parallelogram and with its help we will compose and solve the equation.
So, we know the perimeter of the parallelogram – 50 cm and the length of one of its sides – 10 cm.
The perimeter of a parallelogram is searched for by the formula:
P = 2 (a + b);
Let’s denote by x cm the length of the second side and get the equation:
2 (10 + x) = 50;
10 + x = 50: 2;
10 + x = 25;
x = 25 – 10;
x = 15 cm length of the second side.
Answer: 15 cm; 15 cm; 10 cm.