Answer: 12
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Explanation:
Focus solely on triangle ABD.
Let x be the length of AD. This is the unknown horizontal leg of the triangle. The vertical leg is known, so we'll say b = 16.
The hypotenuse is 20, so c = 20.
Use the pythagorean theorem to find x
a^2 + b^2 = c^2
x^2 + 16^2 = 20^2
x^2 + 256 = 400
x^2 = 400 - 256
x^2 = 144
x = sqrt(144)
x = 12
Segment AD is 12 cm long.
