Math problems, Xuexian help haha

Solution, 1 triangle perimeter 30 + 40 + 50 = 120 area 30x40 2 = 600 (square) 2, parallelogram perimeter 6+ area (6+ = =99 2 = square) 3, perimeter = = = area 5 2x5 = = square).

Perimeter area.

Triangle: 30 + 40 + 50 = 120 30 * 40 * trapezoid: 6 + 6+ (6+

The third:

The first circumference is 120 and the area is 600, the second perimeter is 30 and the area is 189, and the third circumference is 15+ area.

Start by calculating the total amount of money.

It was 48 2/5

then 48 2/5 7/15

240 7/15

A: It cost 112 yuan to buy the tape.

18 meters = 1800 centimeters.

The model is set to be x meters high.

3：200=x：1800

x=27

Let the model be x meters high, and the column equation is 3 200 = x 18The solution is x=

Kid, what are you doing in class?

1. Pi is the ratio of (circumference) to (diameter), which is represented by the letter (.

Leaving two decimal places is about ( ).

2. Draw a circle with a compass, (the center of the circle) determines the position of the circle, and (the radius) determines the size of the circle. with a circle.

Draw a circle with a diameter of 16 cm, and the distance between the legs of the compass should be (8) cm. Draw the perimeter.

Yes, the distance between the feet of the compass should be ( ) cm.

3. About 1500 years ago, there was a great mathematician and astronomer in China (Zu Chongzhi), who calculated.

Out of pi should be between and become the first in the world to put pi.

A person whose value is accurate to 7 decimal places.

4. The ratio of the radius of circle A and circle B is 5:3, the ratio of their diameter is (5:3), and the ratio of circumference is .

5:3), the ratio of area is (25:9).

5. Bend a long iron wire into a circular iron ring, the diameter of this iron ring is (2) dm, and the area is ( ) dm2.

6. The circumference of a circle is to draw the largest square in this circle, the area of the square.

Yes (8cm2).

1. Circumference diameter

2. The radius of the circle is 8 83, and Zu Chongzhi.

Circumference Diameter

The center of the circle has a radius of 8

Zu Chongzhi 5:3 5:3 25:92

4cm²

1. Perimeter radius

2. The radius of the center of the circle is 8

3, Zu Chongzhi.

cm2

1. Pi is the ratio of ( ) to ( ), which is represented by the letter ( ).

Leaving two decimal places is about ( ).

1.1303 liters , at least 209 liters of gasoline ready.

Very simple. It is 2 blocks long and 1 block wide. The ratio of length is: 2:10;The ratio of width is: 1:5 2:10=1:5

x=21*(5/15)=7