A is the 1-sina sign of the second quadrant angle

A is the 1-sina sign of the second quadrant angle

No matter what quadrant angle a is, the sign of sina0 is+
If Sina = 4 / 5, a is the second quadrant angle, then sin2a =?
∵ Sina = 4 / 5, a is the second quadrant
∴cosa=-3/5
∴sin2a=2sinacosa=2×(4/5)×(-3/5)=-24/25
If Sina = 1 / 4 and a is the second quadrant angle, then cosa =?
The second quadrant is cosa
-Root 15 / 4
The square of x minus 6x equals 11 process!
x^2-6x=11
B ^ 2-4ac = 80 = 4 times root 5
X = (6 + 4 times radical 5) / 2 = 3 + 2 times radical 5 or
X = (6-4 times radical 5) / 2 = 3-2 times radical 5
Add 9 to both sides of the equation so that the left side is the square of (x-3)
And then x-3 is the square root of 20, pay attention to the sign
Finally, we can find the value of X by adding 3 to both sides of the equation
The problem of vector system construction in mathematical solid geometry space
I built a left-handed system from one of its vertices. The final cosine value is positive. Will this be different from that of building a right-handed system? I remember the teacher said that building a left-handed system will change the sign of the result. So, do I get the same sine and cosine value as that of building a right-handed system?
A: the angle range between the spatial lines is 0-90 degrees. Therefore, the cosine of the angle is constant. The construction of left-handed system will change the sign of some quantities, that is, it will not change the sign of conventional quantities obtained from the theorem in the process of operation
Given that proposition p: exists x ∈ R, has SiNx + cosx = 2; proposition q: any x ∈ (0, half π) has x > SiNx, then the following propositions are true propositions
A. P and Q B.P or (non-Q) C.P and (non-Q) d. (non-p) and Q
D. (not p) and Q
What is the limit of LIM approaching infinity (2x-3) ^ 5 (X-2) ^ 3 / (2x + 9) ^ 8, and what is the limit of LIM approaching 0 2x SiNx / x + SiNx
In the first problem, since the power is the same, according to the limit theorem of polynomials,
The limit is equal to the ratio of the coefficients of the highest secondary term
It's 32 on the top and 256 on the bottom, so it's 1 / 8
The second problem is to change SiNx into x by using approximate differential,
We get X / 2x = 1 / 2
Lim tends to infinity (2x-3) ^ 5 (X-2) ^ 3 / (2x + 9) ^ 8 = 2 ^ 5 / 2 ^ 8 = 1 / 8
Lim tends to 0 2x SiNx / x + SiNx = (2-cosx) / (1 + cosx) = 1 / 2
Here's what I ask:
1、lim[(2x-3)^5(x-2)^3]/(2x+9)^8=lim[(2x-3)^5(x-2)^3]/(2x+9)^5(2x+9)^3
That is, the denominator is divided according to the third and fifth power, and then combined and multiplied with the numerator respectively
=lim[(2x-3)/(2x+9)]^5[(x-2)/（2x+9)]^3=1*(1/2)^3=1/8
2. LIM (2x sin... Expansion)
Here's what I ask:
1、lim[(2x-3)^5(x-2)^3]/(2x+9)^8=lim[(2x-3)^5(x-2)^3]/(2x+9)^5(2x+9)^3
That is, the denominator is divided according to the third and fifth power, and then combined and multiplied with the numerator respectively
=lim[(2x-3)/(2x+9)]^5[(x-2)/（2x+9)]^3=1*(1/2)^3=1/8
2、lim(2x-sinx)/(x+sinx)=lim[2-(3sinx/x+sinx)]=2-3limsinx/(x+sinx)=2-3x(1/2)=0.5
The special limit limx / SiNx = 1 is used
The above answers are for reference only. If you have any questions, please continue to ask
1. According to the limit determination theorem, the limit is equal to the ratio of the coefficients of the highest order term.
So 32 divided by 256 is 1 / 8.
2. Using IMX / SiNx = 1, X / 2x = 1 / 2
The square of x minus 6x minus 7 equals 0
The square of x minus 6x minus 7 equals 0
(X-7) (x + 1) = 0 (cross multiplication)
X = - 1 or x = 7
Operation of space vector
All operations of space vector, such as vector a minus the module of vector B, vector a plus the module of vector B, vector a multiplying the module of vector b
Single operation is OK. It's better to have modular operation, such as the module of a minus B
|A+B|=sqr(|A|+|B|+2AB)
|A|=sqr(a*a)
|B|=sqr(b*b)
Geometric representation: the sum of three non coplanar vectors is equal to the vector represented by the diagonal of the parallel hexahedron with the three vectors as the adjacent sides. On the modular operation of space vectors: for any two space vectors, it is always possible to
It is known that f (x) is an odd function defined on R, and when x is greater than 0, f (x) = SiNx + cosx, find the analytic expression of F (x) when x belongs to R
If f (x) is an odd function on R, then:
f(x)=-f(-x)
Then:
When X0
f(x)=-f(-x)
=-sin(-x)-cos(-x)
=sinx-cosx
When x = 0
f(0)=-f(-0)=-f(0)
Then f (0) = 0
So:
When x0, f (x) = SiNx + cosx
Odd function
F (- x) = - f (x)
Let f (x) = SiNx + cosx = - f (- x)
So f (- x) = - SiNx - cosx (x > 0)
So f (x) = - sin (- x) - cos (- x) x