Area of the parallelogram is given by:
Area = Base x Height
Base = 8 cm
Height is the perpendicular distance between the base. 6 cm is not the height, but we can use 6 cm and the angle 60 to find the height. See the picture attached with.
The height x is the perpendicular side of the triangle as shown in figure and 6 is the hypotenuse.
So,we can write
cos 60 = x/6
⇒
x = 6 * cos 60 = 3 cm
So, now we can write:
Area of parallelogram = 8 x 3 = 24 cm²