The perimeter of the quadrangle KOPT is 17 cm, KO = 5 cm, OP = 6 cm, PT = KT. Find the length of the side of the CT.

Let’s solve this problem using the equation.

We denote by x the length of the side of the CT.

According to the condition of the problem, the lengths of the sides КТ and РТ are equal, therefore, | РТ | = x.

It is also known that the perimeter of this quadrilateral is 17 cm, the length of the KO side is 5 cm, and the length of the OP side is 6 cm.

The perimeter of any quadrilateral is equal to the sum of the lengths of all 4 sides of this quadrilateral, therefore, we can compose the following equation:

x + x + 5 + 6 = 17.

Solving this equation, we get:

2x + 11 = 17;

2x = 17 – 11;

2x = 6;

x = 6/2;

x = 3 cm.

Answer: the length of the side of the CT is 3 cm.