How many even functions is the left shift of 3cos X - SiN x image? ①√3cos x -sin x =2cos (x + 5 / 6) So, obviously 5 / 6 to the left Can it be written as ①-sin x+√3cos x =2Sin (x + a) (a = Wu / 3) =2Sin (x + V / 3) According to "odd variable, even constant" Do you want to shift "Wu / 6" to the left“ 2Sin (Wu / 6 + Wu / 3) =2Sin (Wu / 2) =2cos x 5 / 6 / 6? Isn't that right?

How many even functions is the left shift of 3cos X - SiN x image? ①√3cos x -sin x =2cos (x + 5 / 6) So, obviously 5 / 6 to the left Can it be written as ①-sin x+√3cos x =2Sin (x + a) (a = Wu / 3) =2Sin (x + V / 3) According to "odd variable, even constant" Do you want to shift "Wu / 6" to the left“ 2Sin (Wu / 6 + Wu / 3) =2Sin (Wu / 2) =2cos x 5 / 6 / 6? Isn't that right?

①-sin x+√3cos x
=2Sin (x + a) (a = Wu / 3)
=2Sin (x + V / 3)
The deformation here is not right. There is no negative sign
①-sin x+√3cos x
=sin(π/3-x)
=-sin(x-π/3)
The answer is the same
This problem is simpler because it is even function or cos

In the four functions defined on R, (1) y = - | x | (2) y = x ^ 2 (3) y = SiNx (4) y = cosx, the number of even functions is?

(1) (2), (4) are even functions,
There are three in total

Advanced Mathematics - find the discontinuity of the function y = x-3 divided by X-2

Denominator x ^ 2-x-2 = (x + 1) (X-2) because the denominator is not 0, the discontinuity point is x = - 1 or 2

Fifth grade volume II mathematical oral arithmetic problems (PEP unit 2)

A piece of rectangular cardboard 10 cm long and 9 cm wide, cut it into the largest square, how much less area than the original?

Ten percent!

What is the ordinate of sine alternating current waveform? It is said that it is the instantaneous value of positive alternating current, voltage or current or electromotive force?

That is, the initial phase is different, with a difference of two Pai
If it's been on for a while, you can't tell the difference
So generally speaking, it is always "sine current or cosine current"
Because the editorial board member couldn't tell the difference between them,
You can't tell the difference. It means you are as good as them

With a rectangular sheet of iron, 100 cm long and 80 cm wide, cut 25 cm square from each corner to make a fuel tank. How much is the volume of the fuel tank

Height of fuel tank: 25cm
Length of fuel tank: 100-25 * 2 = 50cm
Width of fuel tank: 80-25 * 2 = 30cm
Volume: 50 * 30 * 25 = 37500 cm3

For example: distance = speed × time, can be expressed as: S = vt
The workload = work efficiency × work time, how to express in English letters?
Is workload also expressed in S

W=NT

It is known that the radius of the bottom surface of the cone is 4cm, the length of the generatrix is 12cm, and there is a point a on the circumference of the bottom surface. Starting from point a, it moves along the surface of the cone for a circle, and then returns to the original starting point to find the shortest distance of this operation

When the cone is cut along a generatrix and expanded, the cone surface becomes a sector with a radius of 12 and an arc length of 2 * pi * 4. At this time, the problem is equivalent to finding the shortest distance between the two ends of the sector arc, which is of course a straight line, that is, the chord length of the sector. The included angle of the sector is 2 * pi * 4 / 12 = 2 * pi / 3 = 120 degrees. It is easy to find the root 3 with 12 times the chord length, that is 12 * sqrt (3)

On the judgment of decimal addition and subtraction
When calculating the decimal addition and subtraction method, align the decimal point, and then align the end of the decimal. Is that right? for instance

I personally think this sentence is wrong, such as 1.25 + 1.356, even if the decimal point is aligned, the end cannot be aligned