Question

Given the length of three sides of a triangle, which is a right triangle?

Answer 1

Pythagoras, cool.
30^2 is 900
15^2 is 225
26^2 is 676
676+225 isn't 900 so it isn't A.

10^2=100
26^2=676
24^2=576
100+576=676 so B is a right angled triangle. 

Hope this helps :)