"The amount of land resources is relative. Under certain conditions, it will change from less to more." can you understand the meaning of this sentence? Try to see if you can list the conditions from less to more according to the reasons for less variation

"The amount of land resources is relative. Under certain conditions, it will change from less to more." can you understand the meaning of this sentence? Try to see if you can list the conditions from less to more according to the reasons for less variation

For example, with the development of production at the cost of destroying the environment, a large number of soil, air and water sources will be polluted, and eventually the space suitable for human habitation will be smaller and smaller
Another example: through the development of science and technology, improve efficiency, realize the harmonious coexistence of human and nature, not only the environment can be protected, a certain area of production capacity is constantly improved, so that the human living space has been expanded

The arc chord length is 5.1 meters, and the height is 80 cm. What is the arc length,

Arc chord length L = 5.1m, arc height h = 80cm, arc length C? Arc radius R. the center angle of arc is A.R ^ 2 = (R-H) ^ 2 + (L / 2) ^ 2R ^ 2 = R ^ 2-2 * r * H + H ^ 2 + L ^ 2 / 42 * R * H = H ^ 2 + L ^ 2 / 4R = H / 2 + L ^ 2 / (8 * h) = 0.8 / 2 + 5.1 ^ 2 / (8 * 0.8) = 4.464m, a = 2 * arc sin ((L / 2) / R) = 2 * arc sin ((5

How long is the arc of R350 arc 900?

Find the center angle of the circle first=
900/2*350*π
=9/7π；
According to the relationship between the length and the radius, l = √ 2 * r * sin center angle
obtain
The Xuanchang is: l = √ 2 * 350 * sin9 / 7 π

In △ ABC, ab = AC, ∠ ABC = 36 °, D, e are the points on BC, ∠ bad = ∠ DAE = ∠ EAC, then the isosceles triangle in the figure has______ One

In ∵ ABC, ab = AC, ∵ ABC = 36 °, ∵ ACB = ∵ ABC = 36 °, ∵ BAC = 108 °, ∵ bad = ∵ DAE = ∵ EAC, ∵ bad = ∵ DAE = ∵ EAC = ∵ ACB = ∵ ABC, ∵ abd, ∵ ade, ∵ ace, ∵ Abe, ∵ ACD are isosceles triangles

The application of the greatest common factor and the least common multiple
There is a bag of fruit candy, 8 pieces, 8 pieces, 5 pieces more; 6 pieces, 6 pieces, 3 pieces more; 4 pieces, 4 pieces, 1 piece more?

It can be regarded as 8 blocks, 8 blocks, 5 more; 6 blocks, 6 blocks, 3 more; 4 blocks, 4 blocks, 1 more; all can be regarded as 8 blocks, 8 blocks, 3 less; 6 blocks, 6 blocks, 3 less; 4 blocks, 4 blocks, 3 less;
8. The least common multiple of 6 and 4 is 48, 48-3 = 45
A: this generation of fruit candy has at least 45 pieces

In △ ABC, cosa = - 4 / 5, SINB = 5 / 13, find COSC

cosA=-4/5 sinB=5/13
∴A＞90° B＜ 90°
∴sinA=3/5 cosB=12/13
∴cosC
=cos[180°-(A+B)]
=-cos(A+B)
=-cosAcosB+sinAsinB
=-(-4/5)×12/13+3/5×5/13
=48/65+15/65
=63/65

Use the smallest prime number, the smallest composite number, and the number that is neither prime nor composite number to form the largest even number___ ．

According to the meaning of prime number and composite number, the smallest prime number is 2, and the smallest composite number is 4. The number that is neither prime nor composite number is 1. According to the meaning and digit knowledge of even number, the largest even number is 412. So the answer is: 412

The image of inverse scale function y = K1 / X intersects with the image of linear function y = k2-1 in a (2,1),
(1) The analytic expressions of the two functions are obtained respectively. (2) the relationship between the symmetrical point of point a about the coordinate origin and the image of the two functions is judged

(1) By substituting point a (2,1) into the analytic expression of the function, we can get: K1 / 2 = 1,2k2-1 = 1, the solution is K1 = 2, K2 = 1
So the analytic expressions of the functions are y = 2 / x, y = X-1
(2) The point a is symmetric with respect to the origin is A1 (- 2, - 1). It is easy to know that A1 is on the inverse proportion function curve. From the distance formula, d = | - 2 + 1-1 | / √ 2 = √ 2, so the distance from A1 to the primary function is √ 2

Words that change from singular to plural a to e
For example: man --- men

woman women

The axis of symmetry of the parabola y = - x, square = mx-n is a straight line x = - 3, and the value of M, n is obtained through the point (0.4)

The axis of symmetry of parabola y = - X & # 178; + mx-n is x = m / 2 = - 3, M = - 6, then:
The parabola is y = - X & # 178; - 6x-n
If the parabola passes through the point (0,4), then substitute x = 0 and y = 4, and N = - 4
Then:
The parabola is y = - X & # 178; - 6x + 4