How to write the first snow triangle question of 18 trees in the sixth grade

Snow is so foreign to us children in the south, do you know what snow does? Now I'm going to introduce it to you!

Is spring snow good or bad for crops? It depends on the situation. The ground is covered with a layer of snow, which stores a lot of water in the soil layer, which is very beneficial for spring plowing and sowing and the growth and development of crops.

This is especially important during the spring drought in the north. So generally speaking, snow is good for crops, whether it is winter or spring.

If the weather is warm all the time, for example, in March and April, there is a sudden heavy snowfall, the temperature drops significantly, and then there is a frost after the snow. In this way, the crop seedlings cannot withstand the invasion of low temperatures, and the phenomenon of wilting and yellowing will occur. This is certainly detrimental to the crops; If at some point in spring, such as at the end of spring and the beginning of spring, the weather has been relatively cold, and the crops have a certain ability to resist cold, the spring snow at this time, covering the crops, can play a role in keeping warm.

As soon as the sun comes out, the weather immediately warms up, and in this case, the harm to the crops is not great.

So generally speaking, snow in early spring has little effect on crops; The snow that falls after March and April has a greater impact on crops. When spring is always warm, if there is a sudden strong cold wave and heavy snowfall, the damage to crops is even greater.

Students, after listening to my introduction, do you have a deeper understanding of snow?

You don't want to copy, it's best to write it yourself!! 11

x+π/6=x-π/3+π/2；

Therefore, sin(x+ 6)*sin(x- 3)=sin(x- 3)*cos(x- 3).

Using the formula of the double angle of sin, sin(x-3)*cos(x-3)=1 2*sin(2x-2 3).

Therefore, the period is 2 2=

(1) tan(c) / tan(b) = sin(c) / sin(b) *cos(b) / cos(c)

By the sine theorem and the cosine theorem, the right side of the equal sign is equal to c b * a 2+c 2-b 2) (a 2+b 2-c 2) *ab ac).

After simplification, we get (a 2 + c 2 -b 2) (a 2 + b 2-c 2).

Substituting the question condition b 2+3a 2 = c 2 and simplifying it gives tan(c) tan(b) = -2

2) From (1), it can be seen that at least one of the angles b and c is greater than 90 degrees (otherwise it is impossible for one of the angles b and c to be negative).

So a must be less than 90 degrees.

In the range [0,90 degrees], tana increases monotonically and COSA decreases monotonically.

When the maximum value of tana is taken, the minimum value is obtained by cosa.

cos a = (b 2 + c 2-a 2) (2bc), substituting the condition b 2 + 3a 2 = c 2 and then removing a 2 to simplify.

cos a = 1 3 ( 2b c + c b ) = (2 * root number 2) 3, equal sign if and only if 2b c = c b.

In this case, sin a = root number(1- cos2a) = 1 3

So the maximum value of tan a is sina cos a = 1 (2*root2) = (root2) 4

There are many mysteries in the palace of knowledge. (20 points) 1. Apple.

Each tree is equivalent to 4 5 of a pear tree, which is the amount of ( ) as a unit "1", an apple tree has 120 trees, and a pear tree has ( ) trees; If it is known that there are 120 pear trees, there are ( ) apple trees. 2. There are more peach trees than apricot trees 1 6, and the ratio of peach trees to apricot trees is ( ) Apricot trees are peach trees ( ) Peach trees account for the total number of trees of the two trees ( .

There are a lot of short-answer questions. 1.Judging the positive and negative proportions [Anyway, our test paper is, proportional, inverse, disproportionate.

It should be] 2Ask for paved floor tiles, optimistic about the unit. 3.

Find the surface area, the volume [cylinder] and the other forgot, as well as the solution ratio of one side.