Answer:
AD ≈ 80
Step-by-step explanation:
The Pythagorean theorem can be used to write and solve relations between the various edges and diagonals.
AE is the hypotenuse of ΔABE, so you have ...
AE² = AB² +BE²
BE² = AE² -AB² = 65 -52 = 13
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AD is the hypotenuse of ΔACD. We presume the figure is a rectangular prism, so CD = BE. Then you have ...
AD² = AC² +CD²
AD² = 80² +13 = 6413 . . . . . CD² = BE² = 13
AD = √6413 ≈ 80.081
AD ≈ 80
