Answer:
Test each set in Pythagorean theorem, since they are right triangles. 
a^2+b^2=c^2 
a and b are the legs, or the shorter sides, and c is the hypotenuse, or longest side 
(7,11,13) 
7^2+11^2=13^2 
49+121=169 
170=169 
False 
(10,24,26) 
10^2+24^2=26^2 
100+576=676 
676=676 
True 
(12,16,20) 
12^2+16^2=20^2 
144+256=400 
400=400 
True 
(12, 35, 37) 
12^2+35^2=37^2
144+1225=1369
1369=1369 
True 
(13, 15, 19) 
13^2+15^2=19^2
169+225=361
394=361 
False