Answer:
16.1 inches
Explanation:
If a rectangle is cut by a diagonal, it becomes a right angled triangle. Given the length of the diagonal and that of a side, the width can be determined using Pythagoras theorem :√ (a² + b²) = c
10² + w² = 19²
w^2 = 361 - 100
w^2 = 261
w = √261
w = 16.1 inches