Answer: the length of the other side is 16.5 units.
Explanation:
The rectangle has 2 equal and parallel sides. Each of the 4 angles in a rectangle is 90°. This means that the diagonal of the rectangle divides it into 2 equal right angle triangles and the diagonal represents the hypotenuse of both right triangles.
To determine the length of the other side, x, we would apply Pythagoras theorem. It is expressed as
Hypotenuse² = opposite side² + adjacent side²
Therefore
17² = x² + 4²
289 = x² + 16
x² = 289 - 16 = 273
x = √273
x = 16.5 units