Answer:
1) not a right triangle
2) not a right triangle
3) Right triangle
4) Right triangle
Explanation:
To determine if side lengths could be a right triangle
The formula is a^2 + b^2 = c^2
a=is the smallest number
b= the middle sized number
c= the largest number
1) 12,15,20
144+225= 400
Doesn't work so no
2)10,11,15
100+121= 225
Doesn't work so no
3)5,12,13
25+ 144 = 169
works so yes
4) 16,30,34
256 + 900 = 1,156
Works so yes!