The two sides of an isosceles triangle are 5 cm and 11 cm. Find the perimeter of this triangle.

From the conditions of the problem, we know that the triangle is isosceles, therefore, its two sides are equal to each other. Consider the lengths of two sides given to us. Equal sides cannot be equal to 5 cm, since the sum of the lengths of the two sides of the triangle cannot be less than the third side. Therefore, equal sides of 11 centimeters. Find the perimeter:

P = 5 + 11 + 11;

P = 27 cm.

Answer: The perimeter of the triangle is 27 centimeters.