5. (20 points) The quadrilateral connecting the midpoints of the sides of trapezoid $\mathrm{ABCD}$ is a rhombus. Find its area if the height of the trapezoid $\mathrm{BH}=5 \mathrm{~cm}$, the smaller base $\mathrm{BC}=6 \mathrm{~cm}$, and the angle $\mathrm{ABC}$ is $120^{\circ}$.

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# Solution.

![](https://cdn.mathpix.com/cropped/2024_05_06_1ae08a41583c767d264cg-09.jpg?height=405&width=660&top_left_y=1411&top_left_x=181)

$\mathrm{H} \quad \mathrm{P}$