CBSE Class 10 Answered

The un folded card will look like:

Now the Area of square = (side)²

                                            = (10)² = 100 cm²

Folded greeting card would look like:

Area of a semi circle = ( r²)/ 2

                                      = (3.14 x 5 x 5)/ 2 = 39.25 cm²

Area of 4 semi circles = 4 x 39.25 = 157 cm²

The protion shaded in red is the hidden region.

Area of hidden region = Area of 4 semicircles - Area of square

                                        = 157 cm²  - 100 cm²

                                        = 57 cm²