Answer:
32 cm
Step-by-step explanation:
Since this triangle (formed by construction) is a 45 45 90 triangle, this means that the ratio between one of the sides (a) and the hypotenuse (h) is h = a * [tex]\sqrt{2}[/tex]
This means that all of the sides are 8 since 8 * [tex]\sqrt{2}[/tex] is the diagonal. Multiply 8 by 4 to get your answer, 32 cm.