Triangle abc is similar to xyz. which proportion can be used to find the unknown side length

Unknown side length of two similar triangles can be found out by scale factor and any of the side lengths.

Step-by-step explanation:

The similarity is one of the criteria of triangles. Two triangles are similar when their respective sides are in similar ratio or proportion. In layman's term, it can be understood as a condition in which two triangles have similar shapes but not similar sizes.

If ΔABC is similar toΔ XYZ, then their respective sides would be in proportion to each other.

This means AB/XY=AC/XZ=BC/YZ

This common ratio is often termed as "scale factor"

Hence any sides length can be found out if either of the terms (i. e. scale factor, side) is given.