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Area Trapecio Isoceles = h * [(a + b) / 2]

Donde

a = 10 cm

b = 4 cm

h = ?

Area = 28 cm²

28 cm² = h * [(a + b) / 2]

28 cm² = h * [(10 + 4) / 2]

28 = h * [(14 / 2)]

28 = 7h

h = 28 / 7

h = 4

Area Triangulo [BxH] / 2

Donde Base = (10 - 4) / 2 = 6 / 2 = 3 cm²

Area Triangulo = [3 x 4] / 2 = [12 cm²] / 2 = 6cm²

Area sombreada = 6 cm²

Rta : D 6 cm².