Primary 6 math problem calculation process

What is the base area of the cuboid by cutting the bottom circumference of a cylinder with a height of 10 cm into several parts to form an approximate cuboid? What is the volume?

First of all, it is necessary to understand that after cutting the cylinder into several parts, the base area and height are unchanged, and then pieced together into a cuboid;

Algorithm for the bottom area:

Base circumference = *diameter;

Diameter. Diameter = 6 radius = 3, then the original base area = * radius = square centimeter;

The volume is: base area * height = cubic centimeters.

This is an evolution of the formula for deriving the area of a circle! The area of a circle is equal to the circumference of 2*r, then the area of the rectangle is also volume.

1.Divide 3% on both sides of equation 1 to get 150+x+3y=10x+100, 9x-3y=50

Divide 6% on both sides of equation 2 to get 150+2x+y=10y+125 2x-9y=-25

3* -25x=175 x=7 substitution gives y=13 32Sequenced as formula.

2* gets: 8x+3y=-11

Get: 3x-6y=3

2* +: 19x=-19 x=-1 substituting y=-1 x substituting z=0

4x+3y-2z=-7 （1）

5x-6y+z=1 （2）

2x+z=-2 （3）

Solution: (2)*2+(1):14x-9y=-5 (4)(3)*2+(1):8x+3y=-11 (5)(5)*3+(4):38x=-38

x = -1 substituting x = -1 into (3) to get: -2 + z = 2 x = -1, z = 0 to (2) to get : -5-6y + 0 = 1y -1 The solution of the system of equations is {x=-1

y=-1z=0

Question 1: No.

Question 2: {4x+3y-2z=-7

5x-6y+z=1 ②

2x+z=-2 ③

Solution: Multiply 2: 8x+6y-4z=-14

④13x-3z=-13 ⑤

Multiply 3: 6x+3z=-6

⑥19x=-19

x=-1 substitutes x=-1

3z=-26

z=26/3

Substitute z=26 3

y=4/9

The curve is a semicircular arc, and the distance between the two straight segments is equal to the diameter of the semicircular arc.

100 2 meters.

Finding the distance between two straight line segments is actually --- finding"Diameter. "

According to"The standard runway is 400 meters long, with 100 meters in straight sections and curves"It can be seen that the curve is 100 meters long; Two corners into a circle.

That is, the circumference of the circle is 200 meters, and then the diameter is found

200 meters.

The two curves together are a circle, and the distance between the two straight segments is the diameter of the circle, and the circumference of the circle is 200 meters, then the diameter is.

200 meters.

Answer: The distance between two straight line segments is meters.

A curve is an arc of a quarter circle, four curves form a circle, the circumference of the circle is 200 meters, and the distance between the two straight segments is equal to the diameter of the semicircular arc.

200 meters.