Answer:
Triangle B is right
Explanation:
Using the converse theorem of Pythagoras.
If the square of the longest side in a triangle equals the sum of the squares of the other 2 sides then the triangle is right.
Triangle A
longest side squared = 36² = 1296
26² + 18² = 676 + 324 = 1000 ≠ 1296
Hence triangle A is not right
Triangle B
longest side squared = 25² = 625
20² + 15² = 400 + 225 = 625 ← correct
Hence triangle B is right