9^2 + 40^2 = 41^2
(The dark blue box is the correct answer)
1.) Figure out what is 9^2 and 40^2
9 * 9 = 81
40 * 40 = 1600
2.) Now add those two numbers together
1600 + 81 = 1681
3.) Find the square root of 1681
√1681 = 41^2
And that’s how to figure out if a triangle is a right triangle. Hope this helped :D