Find the side of an isosceles triangle, if the two sides are 7 cm and 11 cm long, calculate the perimeter.

Given:
One side is 7 cm.
The second side is 11 cm.
The triangle is isosceles.

Since the triangle is isosceles, then some of its two sides are equal to each other.
There are two options:
1) The base of the figure will be equal to 7 centimeters, then its two sides are 11 centimeters each.
2) The base will be 11 centimeters long, and the sides will be 7 centimeters each.
Let’s calculate both possible perimeters:
1) 7 + 11 + 11 = 29 centimeters.
2) 7 + 7 + 11 = 25 centimeters.
Answer: 25 and 29 centimeters.