High School Math Problems??

f(x)=m*n=(sinx)^2-√3sinx*cosx

3/2sin2x-1/2*cos2x+1/2

sin(2x+π/6)+1/2

1) F(x) is required to be in the monotonically increasing interval of [0,3 2], i.e., finding the monotonically decreasing interval of the function sin(2x+ 6).

Let t=2x+ 6, then 6 t 19 6, and on 2 t sint is monotonically decreasing, i.e., the monotonically increasing interval of f(x) is [ 6, 5 12].

2) f(a)=-sin(2a+ 6)+1 2, then -sin(2a+ 6)+1 2+sin(2a- 6)=1

Simplification gives cos2a=-1 2, so 2a=2 3, thus a= 3

Then from the cosine theorem, we can get cosa=(b 2+c 2-a 2) 2bc

i.e. (b 2 + c 2-a 2) (bc) = 1 (*

And from the area of the triangle is 2 3 to get s = 1 2 * bc * sina , so as to get c = 8

And because b+c=7

Substituting it for (*) gives a 2=25, thus a=5

f(x)=sin²x-√3sinxcosx=（1-cos2x）/2-√3/2sin2x

1-sin（π/6+2x）

The monotonic interval is obvious, and the analysis will not be done here;

f(a）+sin(2a-π/6)=1；That is: sin(2a- 6)=sin( 6+2a), then 2a- 6+ 6+2a= +2k;

Since a is the inner angle of the triangle, a = 4 or 3 4, and a is an acute angle, so a = 4, s =; b+c=7,；The solution yields bc=4 6, b+c =49-8 6;

cosa = (b + c -a ) bc, solution: a = (49 + 8 6-8 3).

The numbers are a bit strange, maybe there is a mistake in which step, the idea is fine, do the math yourself.

Pick out 8 consecutive parking spaces from 10 parking spaces, there are 3 possibilities, to make the truck not adjacent, only need to arrange 5 cars, from the 6 gaps generated by the car, select 3 to make a truck for the mountain, you can achieve the purpose, the order of 5 two cars has a (5, 5) = 120 kinds of possibilities, the truck has a (6, 3) = 120 kinds of possibilities, then the parking space reservation scheme has 3 a (5, 5) a (6, 3) = 43200 kinds.

This question must be a combination of numbers and shapes, and the parabola of the test will inevitably involve the nature of the early line of the parabolic fiber, and the distance from the point of the parabola to the quasi-line is equal to the distance to the focal point. Secondly, there is a proportional relationship, Zheng Yuan should be good at using it, set up unknown numbers to observe the characteristics of the triangle, and then finally choose the appropriate second-level conclusion according to the questions asked.

The specific idea is as follows**.

The formula for the basic non-dispersive equation is: a+b 2 (ab).

The excavation is ba+a b 2 (b a*a b)=2

So the minimum value of b a+a b is 2, and the choice a option is clear.

q is a sufficient and unnecessary condition for p, i.e., q can push p, and p cannot push q In high school mathematics, there is a mantra that small can push big, big can't push small, i.e., q is a true subset of p, q is contained in p

Explanation: A B means A B but A ≠ B

a b means that all elements of a belong to b

To sum up, the construction of railway projects has a vital supporting role in China's economy, and the loss of control of the cost of the project will cause huge losses in human, financial and material resources at one level, and the other level restricts the in-depth development of China's economy, so it is necessary to improve the form and way of risk control of railway project cost. In the process of railway engineering cost risk control, it is required to study the key influencing elements according to the corresponding practical cases, and formulate the corresponding solution means and corresponding solution forms according to such elements and their own nature, so as to improve the construction of the high-speed rail project from the overall level and reflect its corresponding value and significance.

The first is to obtain the knot brightness rule according to the two conditions of the curve and the equation. Secondly, according to the straight line system, the conclusion that the pulse key is over the fixed point is obtained.

For reference, please smile.

A is on the equation 2tx -2y +1 0 and b is on the equation 2tx -2y +1 0, and you will find only two differences: x and x, y and y (both are unknowns, indicating that any number can be taken). Thus, if you replace x and x, y and y with x and y, respectively, you get two identical equations 2tx-2y+1=0.

To sum up, both points A and B are in the equation, and a straight line is determined after two points, so the equation is an equation of the straight line AB. I don't know if I understand you like this, I hope you can understand.

Because the two points a and b are the root of this equation.