Answer:
diagonal = √80 or 8.9
Explanation:
Let's use pythagorean theorem here. Draw a diagonal separating the rectangle. We know that all the angles of a rectangle are 90 degrees. Therefore, we'll have a 90 degree triangle and we can use the pythagorean theorem.
4^2 + 8^2 = diagonal^2
16+64 = diagonal^2
80 =
diagonal = √80 or 8.944