Fold a 20 cm long rectangular paper in half and cut it along the crease to get two identical squares. Calculate the perimeter and area of the original rectangle xiangxi

Fold a 20 cm long rectangular paper in half and cut it along the crease to get two identical squares. Calculate the perimeter and area of the original rectangle xiangxi

Width: 20 △ 2 = 10
Perimeter: (10 + 20) × 2 = 60, perimeter 60cm
Area: 10 × 20 = 200 area: 200 square centimeter

A rectangular white paper strip 20 cm in length and 2 cm in width is folded obliquely and colored on one side. The coloring area is
It's folded up and down
、

Let AB = 2, ad = 20 in rectangle ABCD, and fold upward along the diagonal BD, so that C to e, be and ad intersect F. the coloring area is the sum of △ BDE and △ ABF. From △ Abf ≌ △ EDF, (a, a, s), let AF = EF = x, BF = 20-x, in right angle △ ABF: BF & sup2; = AB & sup2; + AF & sup2;, (20-x) & sup2; = 4 + X & sup2; 4

Fold a rectangular paper in half for three times, and the area of each small rectangular paper is ()
A. 25%B. 50%C. 12.5%

The area of each small rectangle is 12.5% of that of the original large rectangle