Answer:
Step-by-step explanation:
Draw a vertical line through the upper left hand vertex of this parallelogram. This line represents both the "opposite side of the 45 degree angle" and the "height of the parallelogram." It also forms a right isosceles triangle. Using the sine function we can find the "height of the parallelogram."
sin 45 degrees = height/[18√2].
Multiplying both sides by this, we get
height = 18√2·sin 45 degrees = 18/2 units, or 9 units
Then the area of the parallelogram is (9 units)(20 units) = 180 units²
