Some rectangles are not parallelograms

I'm not sure what your asking, but, no, all rectangles are parallelograms.

I found this over the internet, and I hope it helps you understand why a rectangle is always a parallelogram, but a parallelogram is not always a rectangle:

It is true that every rectangle is a parallelogram, but it is not true that every parallelogram is not a rectangle. For instance, take a square. It's a parallelogram — it is a quadrilateral with two pairs of parallel faces. But it is also a rectangle — it is a quadrilateral with four right angles.

step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm

b

step-by-step explanation: