sin157°30′cos22°30′=? π/2

sin157°30′cos22°30′=? π/2

sin157°30′cos22°30′
=sin(180-22°30′)cos22°30′
=sin22°30′cos22°30′
=1/2*sin(2*22°30′)
=1/2*sin(45°)
=√2
sin(2π-α)=-sinα=-4/5
sinα=4/5
π/2
1. Sin 157 ° 30 ′ = sin (180 ° - 22 ° 30 ′) = sin 22 ° 30 ′ (induction)
2sin22 ° 30 ′ cos22 ° 30 = sin45 ° (double angle)
So 2sin157 ° 30 ′ cos22 ° 30 ′ = sin45 ° both
2sin157°30′cos22°30′=sin45/2
2. Sin (2 π - α) = - 4 / 5 = sin - α (induction), Tan (π + α) = Tan α (induction)
In English, does the verb at the beginning of a sentence become ing?
I remember that I always seem to have said it in junior high school, but I also seem to have seen sentences with non - ing forms at the beginning of verbs
Can you give me some examples? Under what circumstances can I use ing and not use it?
What's more, can you tell me what form a sentence can and can't start with, that is, what can and can't be used?
If it's an imperative sentence, use the original form of the verb (in fact, it omits the subject you) seat.Open In this case, the verb ing is called gerund, which is equivalent to a noun
At the beginning of a sentence, if you don't use the subject, you should use the original form. This is an imperative sentence. For example: come here. Stand up
If you are a subject, use a non finite verb, you can use the form of - ing. See is believing
Hello! The beginning of a verb is usually in the form of ing or to + verb prototype, but the imperative sentence is an exception. For example, open the door, please
Hello. The following sentences begin with verbs:
1 come again tomorrow if you can
2 to learn English well isn't as hard as you think
3 learning English well isn't as hard as you think
Generally, the beginning of a verb is to be a subject, and it needs a noun, so the ing form is OK. Generally, to do is OK
Multiplicative meaning of complex number
A complex number can be regarded as a point on a complex plane. However, the square (or multiplication) of a complex number is usually multiplied by a term of an ordinary algebra. Can it be like the square of a complex number? From the geometric point of view, it is the square of the vector from that point on a complex plane to the origin. And the square of the vector is just the square of the real part plus the square of the imaginary part of the real number Fang. That's not contradictory. I read the book. The meaning of complex multiplication is the transformation of the angle on the complex plane. But what's wrong with my idea? Who can help me? Maybe I don't understand my concept thoroughly. Who can explain it to me? I want to have the feeling of sudden realization
But. Isn't the result of multiplication of two vectors a number. Multiplication of complex numbers may result in numbers or vectors. I don't quite understand~
Complex number is actually a kind of number defined by x = a + bi, where I is the symbol of complex number (of course, it is not also complex number, but it will also be classified as real number), thus forming a complex plane. That is to say, each complex number has a unique point corresponding to it on the complex plane, which is equivalent to a vector. The starting point is the origin, and the ending point is
"And the square of a vector is just the square of the real part plus the square of the imaginary part of a real number"! "The square of the real part plus the square of the imaginary part" is not equal to the square of the vector, it means the length of the vector (scalar). "Vector square" also includes the problem of direction!
Solving trigonometric function exercises
1. If the image of the function y = sin2x + acos2x is symmetric with respect to the line x = - Pie / 8, then a is equal to_____
2. If f (x) = 2cos (Wx + P) has f (Pie / 3-x) = f (Pie / 3 + x) for any x belonging to R, then f (Pie / 3) is equal to_____
1: Where α / sin = 1 + and α / sin = 8,
So there is 2 * (- π / 8) + α = - π / 2 + K π K any integer α = - π / 4 + K π, so a = plus or minus 1
2: Because the axis of symmetry is π / 3, I don't know the maximum and minimum, so it is plus or minus 2
-Radical 2
How to add ing to English Verbs
What kind of double ending + ing and what is direct + ing?
Very simple, remember: 1. General direct add, not more 2. E at the end of, remove e, add ing:have-- having; The conditions here must be satisfied: the end of a consonant + the heavy syllable + the closed syllable
Monosyllabic words and auxiliary words should be written in double, most of the other words are direct + ing, but there are also some words ending in e that need to go to E
There are many kinds of things to memorize.
Go to e, double write, direct It's all memorized like this
Monosyllabic words: a vowel letter + a consonant letter ending, double writing plus ing
Disyllabic words: one vowel + one consonant ending with the next vowel stressed, double writing plus ing
The physical meaning of complex multiplication
Complex addition can be regarded as the combination of forces. What is the physical application of complex multiplication
I understand that complex numbers can only be understood from the application of force synthesis. Can you give me an example
Respondent: beastx admires
Complex numbers are very useful for studying physical problems. However, the addition and subtraction method in force work is obviously the opposite, which is wrong. The longest used place is wave. For example, the most common one-dimensional mechanical wave, the phase can be written in the form of e ^ (WT KX), which can be written separately, indicating the contribution of time and coordinates to the phase, Since exponential function is much better than trigonometric function in mathematical treatment, complex number is generally used in all problems involving waves
Work hard
Solving trigonometric function problems
1. Given Tan θ = 2, then sin ^ θ + sin θ cos θ - 2cos ^ θ =?
2. If Tan α = 2, then 3sin α + 2cos α =?
First question: ∵ sin ^ θ + cos ^ θ = 1 ∵ sin ^ θ + sin θ cos θ - 2cos ^ θ = (sin ^ θ + sin θ cos θ - 2cos ^ θ) / (sin ^ θ + cos ^ θ) the numerator is divided by cos ^ θ to get: (Tan ^ θ + Tan θ - 2) / (Tan ^ θ + 1) substitute Tan θ = 2 to get sin ^ θ + sin θ cos θ - 2cos ^ θ = 4 /
When does English verb become ing form
present progressive
The expansion of coefficient and the solution of complex number in high school mathematics
（3x+2y)+(5x-y)=17-2i
For example: 3x + 2Y = 17-2
5x-Y=0
So, isn't it
-How about 2x + y = 15? If so, how can I borrow it? Sorry, I'm not very good at math! Please understand 1
(5x-y) should be followed by an "I", that is to say, X and Y here are real numbers, so we can get the equations 3x + 2Y = 17, 5x-y = - 2. We can get x = 1, y = 7
If the title is correct, that is to say, X and y are plural, more complex
Write the plural of the following words in English
cap task star tree stomach house exercise bus box watch dish class shelf life knife leaf wife half man gentleman policeman woman foot tooth Sheep fish Aircraft deer Janpanese
caps
tasks
stars
trees
stomachs
houses
exercises
buses
boxes
watches
dishes
classes
shelves
lives
knives
leaves
wives
halves
Men
gentlemen
policemen
women
feet
teeth
sheep
fish
aircrafts
deer
japanese
caps,tasks,stars, trees,stomaches,houses, exercises, buses, boxes, watches, dishes, classes, shelves, lives, knives, leaves, wives, halves, men, gentlemen, policemen, women, feet, teeth, sheep, fish,