Answer:
The length is 9 units. The width is 2 units. If you multiply these 2 values (9 x 2) you will get 18 square units for the area of the rectangle.
Step-by-step explanation:
If the area of the triangle is 1/2 the area of the rectangle you will divide 18 by 2.
18/2 = 9.
The area of the triangle is 9 square units.