You would use the pythagorean theorem. a² +b² =c²
side² +side² = hypotenuse²
So for 1) 8² + 15² = c²
64+225=c²
289=c²
√c² = √289
c = 17
2. 7²+24² =c²
49+576= c²
c²=625
√c²= √625
c = 25
3. 5²+13²=c²
25+169=c²
c² = 194
√c² = √194
c = 13.93
4. 24² + 45² =c²
576 + 2025 =c²
c² = 2601
√c² = √2601
c = 51
5.
Plug each choice into the pythagorean theorem. a² +b² =c²
3²+4² = 5²
9+16= 25
25=25
6²+8²=10²
36+64=100
100=100
16²+63²=65²
256+3969=4225
4225=4225
8²+9²=10²
64+81=100
145=100 Since 145 does not equal 100 it is not a right triangle