Answer:
x = 5
Explanation:
using the Pythagorean theorem:
(x-1)² + (x-2)² = x²
x²-2x+1 + x²-4x+4 = x²
reduce:
2x²-6x+5 = x²
subtract x² from each side:
x²-6x+5 = 0
(x-1)(x-5) = 0
x=1 but because shorter leg would be 0, a triangle would be impossible.
x=5