Answer:
8
Step-by-step explanation:
The length of the top segment is the difference of its x-coordinates: 7-2=5.
The length of the bottom segment is the difference of its x-coordinates: 9-(-2)=11.
The length of the midsegment is the average of the lengths of the top and bottom segments:
(5 +11)/2 = 16/2 = 8
The length of the midsegment is 8.
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Additional comment
You can check this by drawing a midline at y = 1.5. It intersects AD on the y-axis (x=0), and intersects BC at x=8. The length of the midline is the difference of those x-coordinates: 8-0 = 8.
