Answer: 4
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Step-by-step explanation:
The diagonals of a rhombus bisect each other (i.e. split in half).
This means YW = 6 splits in half to YV = 3 and VW = 3.
The diagonals of a rhombus are also perpendicular, so we have four right triangles. Focus on triangle WVX.
It has these sides:
- VX = unknown leg
- VW = 3 = the other leg
- XW = 5 = hypotenuse
We'll use the pythagorean theorem to find the missing leg.

This means VX = 4
Triangle WVX is a 3-4-5 right triangle. This also applies to the other right triangles because they are rotated and reflected copies of each other.