Area = 9*6 = 54 square meters
You multiple one side by the other, so 10 x 10 = 100 square meters.
A parallelogram whose sides are equal in length is always a rhombus. In addition, it may be a rectangle. If it's a rectangle, then it's also a square.
If a rectangle has its length equal to its width, then all four sides are of equal length and it is a square.
10 x 10 = 100 square metres. Which is a square area 10 metres by 10 metres. Or a rectangle whose length and width can be multiplied together to produce 100.
Its length works out as 15 meters when its width is 4 meters.
A rectangle with width 4 can have any length!
It could be a square whose sides are sqrt(1/3) of the original square or a rectangle whose length is the same as the side of the square but whose width is one third of that. There are many other possibilities.
A square is a rectangle whose adjacent sides are equal.
You are describing a rectangle NOT a square!
Area: 11.5*7.5 = 86.25 square cm