A new iron mail box with a length of 50cm, a width of 40cm and a height of 78cm has been installed at the entrance of Guanghua Street. How many square centimetres of iron sheet is needed to make this mailbox?

A new iron mail box with a length of 50cm, a width of 40cm and a height of 78cm has been installed at the entrance of Guanghua Street. How many square centimetres of iron sheet is needed to make this mailbox?

（50×40+50×78+40×78）×2
=（2000+3900+3120）×2
=9020×2
=18040 (square centimeter);
A: at least 18040 square centimeter iron sheet is needed to make this mailbox

The base of a triangle is 8 cm and the height is 5 cm. What is the area Math

=8 * 5 / 2 = 20 square centimeter

Two triangles with the same area. One is 12cm long and twice as high as the bottom. The other is 8cm high. How many centimeters is the bottom where the height is?

Let the base of this height be H
From the meaning of the title
The bottom of a triangle is 12 and the height is 24
Because the area is equal
therefore
(12*24)/2=(8*h)/2
The solution is h = 36

Two triangles of equal area, one is 12 cm long at the base, twice as high as the base; the other is 8 cm high, and the bottom is where the height is

12×12×2÷8
=288÷8
=36 (CM)

The area of a triangular iron sheet is equal to that of a circular iron sheet with a radius of 50 mm. If the bottom edge of a triangular iron sheet is 250 mm long, then the height of the triangle on this bottom edge is______ Mm

3.14×502×2÷250，
=3.14×2500×2÷250，
=3.14×20，
=62.8 (mm)
A: the height of the triangle on this bottom is 62.8 mm
So the answer is: 62.8

A triangle and a parallelogram have the same area and the same bottom. If the height of the triangle is 18 cm, how many centimeters is the height of the parallelogram

The height of the parallelogram is 18 × 2 = 36 cm

The area of a parallelogram is equal to the area of a triangle. It is known that the height of the base of a parallelogram is 10 cm and the bottom of the triangle is 20 cm. Find the height of the triangle

18 * 10 = 180 (cm ^ 2) this is the area of a triangle and a parallelogram
180 * 2 = 360 (cm ^ 2) this is the area of the parallelogram formed by triangles
360÷20=18（cm^2）
A: the height of the triangle is 18 cm

If the base of a triangle is 18 cm, the base of a parallelogram is () cm A. 9 B. 18 C. 36

18 △ 2 = 9 (CM)
A: the base of the parallelogram is 9 cm
Therefore, a

The area of a triangular iron sheet is equal to that of a circular iron sheet with a radius of 50 mm. If the bottom edge of a triangular iron sheet is 250 mm long, then the height of the triangle on this bottom edge is______ Mm

3.14×502×2÷250，
=3.14×2500×2÷250，
=3.14×20，
=62.8 (mm)
A: the height of the triangle on this bottom is 62.8 mm
So the answer is: 62.8

The ratio of top to bottom of trapezoid is 3:4, the area of shadow triangle is 18 square centimeter, and the area of blank triangle is 3:4

The area of the shadow triangle with the bottom as the bottom and the blank triangle: 18 ^ (3 ￣ 4) = 24 square cm
The area of the shadow triangle with the bottom as the bottom: 18 × (3 ￣ 4) = 13.5 square cm