Trigonometric function exercises 1. Given that the terminal edge of angle α is on the ray y = (- √ 3) x (x ＜ 0), the value of sin α + cos α is obtained There is a point P (1, - 2) on the terminal edge of angle α Find: 1) the value of sin (α + Half) 2) Cos (α + pie) 3. If there is a little (- 4, a) at the end of the ten third faction Find the value of A 4. Given cos α = two-thirds of negative, find: 1 + Tan & sup2; α

Trigonometric function exercises 1. Given that the terminal edge of angle α is on the ray y = (- √ 3) x (x ＜ 0), the value of sin α + cos α is obtained There is a point P (1, - 2) on the terminal edge of angle α Find: 1) the value of sin (α + Half) 2) Cos (α + pie) 3. If there is a little (- 4, a) at the end of the ten third faction Find the value of A 4. Given cos α = two-thirds of negative, find: 1 + Tan & sup2; α

1. The slope of ray y = (- √ 3) x (x < 0) k = - √ 3 = Tan α,
From the formula, α = 2 π / 3 + 2K π, K ∈ n
sinα=sin(2π/3+2kπ）=sin（2π/3）=√3/2.
cosα=cos(2π/3+2kπ）=cos（2π/3）=-1/2.
So sin α + cos α = (√ 3-1) / 2
2. The distance between origin O and point P is equal to √ 1 ^ 2 + (- 2) ^ 2 = √ 5
sin（α+π/2）=cosα=-2/√5.cos(α+π)=-cosα=2/√5 .
3. A little (- 4, a) is known from the end of the ten third faction of Jiao
The final edge of the angle is on the ray y = (- A / 4) x (x < 0) composed of the origin and point P
The slope of ray y = (- A / 4) x (x < 0) is k = (- A / 4) = Tan (10 π α / 3), and 10 π α / 3 = arctan (- A / 4)
So α = 3 arctan (- A / 4) / 10 π is obtained
4, cos α = minus two thirds, (COS α) ^ 2 = 4 / 9, then (sin α) ^ 2 = 1-4 / 9 = 5 / 9
1+tan²α =1+(sinα/cosα)^2=1+sin²α/cos²α =1+(5/9）/（4/9)=9/4
Trigonometric function exercises
In the acute triangle ABC, the opposite sides of the inner angles a, B and C are a, B and C respectively, if a = 6 and SINB = [(radical 3) b] / 12
(1) Angle a
(2) If the area of △ ABC is 6 times the root sign 3, find B and C
sinB=√3b/12
b/sinB=12/√3=4√3
Sine theorem
a/sinA=b/sinB
A=6
∴sinA=√3/2
Acute triangle ABC
∴A=60°
(2)
Triangle area = 1 / 2 * BC * Sina = 6 √ 3
∴bc=24
Cosine theorem
cosA=(b²+c²-a²)/(2bc)
bc=b²+c²-36
24+36=b²+c²
b²+c²=60
Combined with BC = 24, we got the conclusion
b=4√3,c=2√3
Or B = 2 √ 3, C = 4 √ 3
The plural of key, key, which is a vowel?
E, of course
Why not the first one at the beginning of every letter?
On the plural of nouns, O is preceded by a vowel letter and S. why is piano's o preceded by a consonant letter N and S?
You've made a mistake in your concept. Things with life end with O and add es. If they don't, add S. here's a pithy formula for you. Remember that Negroes heroes love potatoes and tomatoes, and others usually add s, such as radios pianos
For example, zoo, s, hero, ES and piano are inanimate, so you can try to find a few more
All the differences between the plural if and while of bamboo
bamboos
1 lead to the object clause, meaning "whether or not"; 2 if for oral, two words can be common I wonder while (if); 3 can only use the while to lead the clause for prepositional object or infinitive phrase; 4 whether.or We can only use whether
bamboos
In general, it can be interchanged, but in the following cases, when is used instead of if:
1. Lead subject clause, predicative clause and appositive clause;
2, used after preposition or after or not
3. When used after the verb discuss, etc
Bamboo is living, plural plus es.
Why add s to the complex number?
OO ends with S
Because they have no life
For living o-ending words like tomato, pluralize with ES
What is kangroo?
If it's kangaroo, why do kangaroos and bamboo on the second floor have no life and tomatoes have life?
This is a special usage formed by history. Just remember it. There is no reason
In addition, bamboo is bamboo, how can it have no life
Because it's a double vowel ending!
Is bamboo a countable noun or an uncountable noun?
There is some bamboo in the garden
There are many kinds of bamboos in the garden
When your questions are answered, please respect the labor achievements of the respondents,
Use much when it is uncountable
Uncountable
It's the same as food and fish. When the general term is uncountable, when the category is countable.
How to change words into plural, when to add es, or to add ies and S. please give me a brief description
1. Most nouns add s directly at the end of the word: school schools, apple apples, book books, desk desks
2. For nouns ending with s, x, SH, CH, etc., add es: bus buses, box boxes, watch watches, dish dishes at the end
3. With the noun of "consonant + Y", change y into I and add es: fly flies, family families, baby babies
4. For nouns ending with F / Fe, change f / Fe into V and add es: knife knives, life lives
5. Nouns ending with O: living adders: tomato tomatoes, potato potatoes, Negro Negroes, hero heroes,
Inanimate plus s: photo photos, radio radios, zoo zoos, piano pianos
Plural of irregular nouns:
1. Simple and plural homographs: fish, deer, sheet, Chinese, Japanese,
2. Special changes: child children, ox oxen, man men, woman women, mouse mice, foot feet, tooth teeth, goose geese
Add es at the end of the word o, CH, s, x, sh,
If not, then add s,
The special one is have has
Add y to ies at the end of the word.
Add es. when the word ends with O, except for photo, etc
When a word ends with y, y is added with ies, except for boy
The third one should be a vowel with a, e, O, U
In English, when does a noun ending in Y become plural without changing it to ies and adding s directly
In English, when does a verb ending in e become an adverb without removing E and adding ly directly
Words ending with y depend on whether the penultimate letter is a vowel (a, e, I, O, U). If it is a vowel, add s directly; if it is not a vowel, remove y and add ie
It ends with a vowel and y.
When y is preceded by a vowel, such as boy -- boys
English words to y + ies
cities
countries
libraries
bodies
The plural number of tens of numerals is
difficulities
cities
countries
libraries
bodies
The plural number of tens of numerals is
difficulities
babies
forties
sixties
When a word ends in Y and becomes plural, it depends on the first letter of Y. if it is a consonant, change y to I and add es. If it is a vowel, you can add s directly! For example, family, which is l before y, will be changed into families.
Idiocy
family