The perimeter of an isosceles triangle is 189cm, and the length of one of the sides is 58cm

The perimeter of an isosceles triangle is 189cm, and the length of one of the sides is 58cm, find the length of the other two sides of this triangle, consider two solutions.

Method I.
Suppose the known side is the base of the triangle.
Consequently, the unknown parties are equal. We denote each by x cm.
Let’s make the equation:
x + x + 58 = 189;
2x = 189 – 58;
2x = 131;
x = 131: 2;
x = 65.5 cm.
Answer: 65.5 cm.

Method II.
Let’s say the known side is the side. Then the second side will also be equal to 58 cm.
So the base of the triangle is x centimeters.
Let’s make the equation:
x + 58 + 58 = 189;
x = 189 – 58 – 58;
x = 73 cm.
Answer: 58 cm and 73 cm.