The triangle is a right angle triangle.
Explanation:
Given,
The lengths of the triangle are 8 cm, 19.2 cm and 20.8 cm.
To find whether the triangle is right angled.
Formula
By Pythagoras theorem we know that if any triangle satisfies the condition 
hypotenuse² = base²+ perpendicular² there triangle will be right angled.
Now,
8²+19.2² = 64+368.64
 = 432.64
 = (20.8)²
It satisfies the Pythagoras theorem. 
Hence it is a right angle triangle.