A proportion which solves for the distance between D and E is: 9/6 = 15/x.
The properties of similar triangles.
In Geometry, two (2) triangles are said to be similar when the ratio of their corresponding sides are equal and their corresponding angles are in congruence.
By applying the properties of similar triangles, we have this expression:
AB/DE = BC/CD
Substituting the given parameters into the expression, we have;
9/6 = 15/x.
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