Final answer:
To find the width of the rectangle, you can use the Pythagorean theorem. In this case, the width of the rectangle is approximately 19.4 inches.
Step-by-step explanation:
To find the width of the rectangle, we can use the Pythagorean theorem which states that the square of the length of the diagonal is equal to the sum of the squares of the length and width of the rectangle.
In this case, the diagonal length is 21 inches and the length is 8 inches. Let's denote the width as x. So, we have:
21^2 = 8^2 + x^2
Solving this equation for x, we get:
x^2 = 441 - 64
x^2 = 377
x ≈ 19.4 inches
Therefore, the measurement closest to the width of the rectangle is 19.4 in.