A rectangular sheet of iron is 24 cm long. After subtracting the square with side length of 3 cm from the four corners, it is welded into a rectangular sheet iron box without cover. The volume of the box is 486 cubic cm. How many cm is the width of the original rectangular sheet iron? Good points for giving reasons

A rectangular sheet of iron is 24 cm long. After subtracting the square with side length of 3 cm from the four corners, it is welded into a rectangular sheet iron box without cover. The volume of the box is 486 cubic cm. How many cm is the width of the original rectangular sheet iron? Good points for giving reasons

Suppose the width of the original rectangular sheet is x cm
(24-3-3)*(X-3-3)*3=486
54(X-6)=486
X-6=486/54
X-6=9
X = 9 + 6 = 15 (CM)
The original width of the rectangular sheet is 15 cm

From the four corners of a piece of 26 cm long sheet iron, cut off four small squares with side length of 3 cm, and then connect them into a rectangular iron box. The volume of the box is 840 cubic cm. How many cm is the original width of the sheet iron?

The length of the box: 26-3-3 = 20 (CM); the width of the box: 840 ／ (20 × 3) = 840 ／ 60, = 14 (CM); the original width of the iron sheet: 14 + 3 + 3 = 20 (CM); a: the original width of the iron sheet is 20 cm

From the four corners of a piece of 26 cm long sheet iron, cut off four small squares with side length of 3 cm, and then connect them into a rectangular iron box. The volume of the box is 840 cubic cm. How many cm is the original width of the sheet iron?

The length of the box: 26-3-3 = 20 (CM); the width of the box: 840 ／ (20 × 3) = 840 ／ 60, = 14 (CM); the original width of the iron sheet: 14 + 3 + 3 = 20 (CM); a: the original width of the iron sheet is 20 cm

Cut four 3cm squares from the four corners of a 26cm long sheet of iron, and then weld them into a rectangular iron box with a volume of 840m and 179; to find the original width

Length of iron box = 26-3-3 = 20 (CM)
Width of iron box = 840 △ 20 △ 3 = 14 (CM)
The width of the original sheet is 14 + 3 + 3 = 20 (CM)
A: the original width of the iron sheet is 20 cm

Know that the center angle is 120 degrees, and the upper and lower radii are 10cm and 20cm

Bus L = 20 / cos30-10 / cos30 = 20 * (1 / 3) ^ (1 / 2)
S=πRl-πrl=200*(1/3)^(1/2)π

In the circle of 4cm in diameter, the area of the sector of 5cm in arc length is______ ．

Circumference of circle: 3.14 × 4 = 12.56 (CM), area of circle: 3.14 × (42) 2 = 3.14 × 4 = 12.56 (square cm), sector area: 12.56 × (5 △ 12.56), = 12.56 × 125314, = 5 (square cm); answer: sector area is 5 square cm, so the answer is 5 square cm

Given that the center angle a of a sector OAB is 120 degrees and the radius R is 6, the arcuate area of this sector can be obtained
The arcuate area is equal to the sector area minus the area of the triangle AOB
S = π × 6 & # 178; × (120 / 360) - (1 / 2) × 6 × 6 × sin0120 ° = 12 π - (9 root sign 3), where the sin120 degree of this formula is obtained,

Let OD ⊥ AB be D, then od = 1 / 2oa = 3, ab = 2bd = 6 √ 3
Arcuate area = sector area - △ AOB area = 120 π × 6 & # 178 / / 360-3 × 6 √ 3 △ 2 = 12 π - 9 √ 3
The calculation of triangle area (1 / 2) × 6 × 6 × 120 ° is not suitable for junior middle school students
Calculate with the base × height △ 2 of isosceles triangle, use the special angle and Pythagorean theorem to calculate the base and height

1. The arc length of the sector is a, the radius is r, the sector area is 2, and the concentric angle of the sector is 150 degrees. Then the area of the sector is equal to the area of the circle where the sector is located
3. If the radius of circle O is 4cm and one of the arcs is 2cm long, what is the central angle of the arc

1.1/2ar
2.150/360=5/12
3.2π=(nπ*4)/180 n=90°

How to find the central angle of a sector circle needs a formula, the arc length also needs the area of the circle by the way. Why do you want to do this
To put it simply, I have a poor foundation

Center angle: L / R
Arc length: R * a (center angle)
Area of circle: 1 / 2 arc length * center angle

Two squares, side length is 8 cm, 12 cm respectively, seek shadow part area?
The picture became rectangular

Because the upper white triangle is similar to the lower white triangle
Therefore, the ratio of high to low is 12:20 = 3:5
So the height of the lower white triangle is 5 / (3 + 5) of the side length of the big square
So the height is 12 × 5 / 8 = 7.5
So the area of the lower white triangle is 7.5 × (8 + 12) / 2 = 75
Shadow area = total area - upper white triangle - right white triangle - lower white triangle
=Total area - half large square - lower white triangle
=8×8+12×12- 12×12/2 -75
=64 + 144 - 72-75
=61