A. To find the area of a parallelogram, multiply the base by the height.

- Base = 3 cm

- Height = 4 cm

- Area = base x height

- Area = 3 cm x 4 cm

- Area = 12 cm²

Therefore, the area of the parallelogram is 12 cm².

B. To find the area of a triangle, multiply the base by the height and divide the result by 2.

- Base = 5 cm

- Height = 8 cm

- Area = base x height / 2

- Area = 5 cm x 8 cm / 2

- Area = 40 cm² / 2

- Area = 20 cm²

Therefore, the area of the triangle is 20 cm².

C. To find the area of a trapezoid, multiply the sum of the bases by the height and divide the result by 2.

- Base 1 = 6 m

- Base 2 = 12 m

- Height = 8 m

- Area = (base 1 + base 2) x height / 2

- Area = (6 m + 12 m) x 8 m / 2

- Area = 18 m x 8 m / 2

- Area = 144 m² / 2

- Area = 72 m²

Therefore, the area of the trapezoid is 72 m².