Question

how many rectangle can be formed in 21 equal squares size 1×1 cm​

Answer 1

Answer:

21cm rectangle

Step-by-step explanation:

If we cut 21cm rectangle then it become 21 square pieces

Answer 2

Answer: 37

Step-by-step explanation:

Every rectangle is uniquely determined by its length and its height.

A rectangle of length = l and height = h then l * h <= n is considered equivalent to a rectangle with length = h and height = l provided l is not equal to h. If we can have some sort of "ordering" in these pairs then we can avoid counting (l, h) and (h, l) as different rectangles. One way to define such an ordering is:

Assume that length <= height and count for all such pairs such that length*height <= n.

We have, length <= height

or, length*length <= length*height

or, length*length <= n

or, length <= sqrt(n)