1) S = base x altura / 2 base = 2S/altura
sustituimos valores
base = 2 x 14 / 4 = 7 cm
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altura = 2 S/ b = 2 x 735 / 42 = 35
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Area trapecio = (B + b ) h / 2
despejando B = (2A / h) -b = (2 x 120/ 8 ) - 10 = 20