Answer:
third side = 9
Step-by-step explanation:
Using Pythagoras' identity on the right triangle.
The square on the hypotenuse is equal to the sum of the squares on the other 2 sides.
let the third side be x, then
x² + 40² = 41², that is
x² + 1600 = 1681 ( subtract 1600 from both sides )
x² = 81 ( take the square root of both sides )
x = = 9
The third side is 9