How do I find the area of the shaded part

Question

Image : https://m.imgur.com/14oU6ta

(sorry I don't have reps to post the image directly)

This is a square made up by 4 equal 90 degrees sectors which 1 side of it is equal to 7cm(actually the radius)

I found the area of these:

1 sector = 38.5

Square - 1 sector = 10.5

1 sector - (square - 1 sector) = 28

I got this question from a friend of mine I tried many ways to do this also tried making equations considering algebra (namig x, y, z)

I don't have any idea to solve that now :(

Also I made my account here specially for this question

THANKS IN ADVANCE

Answer 1

This question has been answered in many different ways, here are two of them:

Here is the second solution: