Answer:
8 cm and 9 cm
Step-by-step explanation:
To estimate the sides of triangle we must understand that any side of a triangle is greater than the differences between any two sides and also less than the sum of the two sides. 
 In this problem; 
 One of the sides is 13cm;
 According to our theorem, this sides is less than the sum of the other two sides and greater than difference between the two sides. 
 8 cm and 9 cm is the correct choice; 
 if the other two sides are 8cm and 9cm; 
 9cm - 8cm = 1cm
 9cm + 8cm = 17cm
13cm is in between them.