Răspuns:
b = 10 dm ; B = 30 dm ; h = 20 dm
Explicație pas cu pas:
A trapez = 400 dm²
A trapez = (B+b)·h:2
b/B = 1/3 => B = 3b
h = (B+b)/2 = (3b+b)/2 = 2b
A trapez = 4b·2b:2 = 4b² = 400dm² =>
b² = 400:4 = 100 => b = √100 => b = 10 dm
B = 30 dm ; h = 20 dm
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