Answer:
20 cm²
Step-by-step explanation:
Look at the diagram attached.
If the height is 4cm, we will have two sides that are 4cm for our rectangle.
We can label the other sides as x.
They are both x since opposite sides of a rectangle are equal in length.
We can make an equation with our perimeter:
[tex]2(4) + 2(x) = 18\\8 + 2x = 18\\2x = 10\\x = 5[/tex]
Now that we know the length & height, we can calculate the area:
4 × 5 = 20 cm²
