In a 45-45-90 triangle, the legs are equal and the lengths of the legs can be represented as
To find the length of the hypotenuse
Substituting the length of the leg:
Now we can calculate
Next, we can find the perimeter
Substituting the value we calculated for the hypotenuse:
Rounding to the nearest tenth:
Therefore, the perimeter of the triangle is 17.1 cm.