Verified answer

Answer:

The third side is 12.5.

Step-by-step explanation:

Add the sides we know together then subtract it from the perimeter.

24.8+15.6=40.4, 52.9-40.4=12.5.

Answer:

12.5 cm

Step-by-step explanation:

Perimeter=Sum of all sides

Let the unknown side be "x".

24.8+15.6+x=52.9

x+40.4=52.9

x=52.9-40.4

x=12.5

Therefore the third side =12.5 cm