A rectangular playground, its perimeter is 250 meters, length and width ratio is 3:2, the playground area is how many square meters?

A rectangular playground, its perimeter is 250 meters, length and width ratio is 3:2, the playground area is how many square meters?

3 + 2 = 5 (shares), length: 250 ／ 2 × 32 + 3, = 125 × 0.6, = 75 (meters), width: 250 ／ 2 × 22 + 3, = 125 × 0.4, = 50 (meters), area: 75 × 50 = 3750 (square meters); answer: the playground area is 3750 square meters,

() - 3 + () - 5 + () - 7 ≈ 1.16?

Add a number in the bracket first, let's set X in the bracket, 71x / 105 = 1.16, x = 3.2

A 490 meter long train passes the 1030 meter long bridge in 1 minute and 20 seconds, and then passes a tunnel in 40 seconds at the same speed. How long is the tunnel?

The length of the bridge + the length of the train before getting on the bridge + the length of the train after getting off the bridge, this is the train passing through the bridge completely, so the bridge length + 2 train length / 2 is the speed of the train passing through the bridge, and the time of passing through the tunnel is 1 / 2 of the time of passing through the bridge, so the tunnel length is 1 / 2 of the bridge length + 2 train length

Let's know that AB is equal to 2 cm, CE is equal to 6 cm, CD is equal to 5 cm, AF is equal to 4 cm, and there are two right angles to find the area of ABCD

If AC is connected, it becomes two triangles, ADC and ABC. If ABC has known the base AB = 2 and the height is CE = 6, then the area of ABC is 2 × 6 △ 2 = 6. If DC = 5 and the height is AF = 4, the area of ADC is 5 × 4 △ 2 = 10 and the area of ABCD is 10 + 6 = 16

How many light years and kilometers are the nearest stars to the earth
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The nearest star to the earth is the nearby star, which is 4.22 light years away from the earth

The following two mobile phone billing tables
Mode one mode two
The monthly rent is 50 yuan / month and 25 yuan / month
Local call fee 0.30 yuan / min 0.5 yuan / min
(1) One month local call time is 150 minutes and 300 minutes. How much is the charge for each of the two mobile phone billing methods?
(2) Will two kinds of mobile phone billing methods be the same? Please explain how to choose to save money

1. The local call time of one month is set to be 150 min. according to the mode of one pay X Yuan and two pay y yuan
X-50 = 0.3 * 150, x = 95
Y-10 = 0.5 * 150, y = 85
Set a local call time of 300 min in one month, and pay X Yuan in one way and Y yuan in two ways
X-50 = 0.3 * 300 and x = 140
Y-10 = 0.5 * 300 and y = 160
2. Set the call time to X minutes. The two mobile phone billing methods charge the same
50+0.3x=10+0.5x
The solution is x = 200
When one month local call time is less than 200 minutes, two ways to save money
When the local call time is more than 200 minutes in a month, there are two ways to save money

As shown in the figure, in the isosceles trapezoid ABCD, ad ∥ BC, m and N are the midpoint of AD and BC respectively, and E and F are the midpoint of BM and cm respectively. (1) prove that the quadrilateral menf is a diamond; (2) if the quadrilateral menf is a square, please explore the quantitative relationship between the height of the isosceles trapezoid ABCD and the bottom BC, and prove your conclusion

(1) It is proved that: ∵ quadrilateral ABCD is isosceles trapezoid, ∵ AB = CD, ∵ a = ∵ D. ∵ m is the middle point of AD, ∵ am = DM. (2 points) ≌ ABM ≌ DCM. (1 point) ≌ BM = cm. (1 point) ∵ e, F, n are the middle points of MB, cm, BC respectively, ∵ en, FN are the median lines of △ BMC,