As shown in the figure, Xiao Hong cuts a 4 cm wide strip from a square, and then cuts a 5 cm wide strip from the remaining rectangular paper along the direction parallel to the short side. If the area of the strips cut twice is exactly the same, what is the area of each strip? What is the area of the original square?

As shown in the figure, Xiao Hong cuts a 4 cm wide strip from a square, and then cuts a 5 cm wide strip from the remaining rectangular paper along the direction parallel to the short side. If the area of the strips cut twice is exactly the same, what is the area of each strip? What is the area of the original square?

Suppose the side length of the square is xcm, then according to the meaning of the question: 4x = 5 (x-4), the solution is: x = 20. Then 4x = 80 (cm2), 20 × 20 = 400 (cm2). Answer: the area of each strip is 80cm2, the area of the original square is 400cm2

A square with a side length of 6cm and a shadow in the shape of a tree leaf. Calculate the shadow area

Because the total area of the two right angle sectors is the area of the square plus the area of the shadow, so cutting the area of the square with the area of the two sectors is the shadow area, that is, 2 * 3.14 * 6 * 6 / 4-6 * 6 = 20.52 square centimeters

Perimeter of shadow part: there is a leaf shape in the square with a side length of 4

Is the shadow leaf shaped?
The girth of leaf shape is 2 * 2 * π * r / 4 = 4 π
=12.56
If the shadow part is other part, the perimeter is 4 π + 4 * 4 = 16 + 4 π
=28.56

The length of a rectangle is 20cm. If the length is increased by 5cm, the width should be decreased by ()% to keep the area unchanged

5 / 20 = 25%
If the area remains unchanged, the width should be reduced by 20%
The area can be 1
The original width is 1 / 20, and the later width is 1 / 25
Reduced: (1 / 20-1 / 25) = 1 / 100
Reduction ratio: (1 / 100) △ 1 / 20 = 20%