# Four Points on a Semicircle

Geometry Level 3

A semicircle has $$AB$$ as the endpoints of its diameter, and $$AB= 400$$. Points $$C$$ and $$D$$ are on the circumference of the semicircle such that $$AD = BC = 100$$. What is the length of $$DC$$?

Details and assumptions:

• Lengths given are always the straight line distance between two points, unless otherwise indicated.
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