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Answer:
6 cm
Explanation:
The area of the parallelogram is the same, either way you figure it.
A = bh
A = CD(length ⊥ to CD)
A = (9 cm)(8 cm) = 72 cm²
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A = AD(length ⊥ AD)
72 cm² = (12 cm)(length ⊥ AD)
(length ⊥ AD) = (72 cm²)/(12 cm) = 6 cm
The perpendicular distance of AD from BC is 6 cm.