In △ ABC, if ∠ C = 90 °, B = 2 ∠ a, then cosa = (), tanb = ()

In △ ABC, if ∠ C = 90 °, B = 2 ∠ a, then cosa = (), tanb = ()

∠A+∠B+∠C=180°
∠A+2∠A+90°=180°
3∠A=90°
∠A=30°
∴cosA=cos30°=1/2
tanB=tan60°=√3/2

Put, where, up, did, tent, you, your 2,
around

1 Where did you put your tents
2 Mary showed me around her school yesterday afternoon .
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Put an isosceles right triangle ABC in the right angle coordinate system, the angle ACB = 90 degrees, a (0,2) C (- 1,0), B in the second quadrant
(1) Finding the coordinates of point B
(2) If the parabola y = ax ^ 2 + AX-2 passes through point B, find the analytical formula of the parabola
(3) Is there any point P (except point B) on the parabola in (2) so that the triangle ACP is still an isosceles right triangle with AC as the right side? If so, find the coordinates of all points P; if not, explain the reason

Coordinates of point B (- 3,1)
A = 1 / 2, y = 1 / 2x ^ 2 + 1 / 2x-2
There is no isosceles right triangle P (- 2,3) or (2,1) or (1, - 1) with AC as the right side, which is not on the parabola in (2)

The synonym of "Yi", the synonym of "Gao", the synonym of "Si", and the antonym of "Tong"

A synonym for Yee: Yee
The synonyms of Gao: Shuo, Shuo
The synonym of thinking: Thinking
The opposite of the same: different

If the area of Δ ABC is (1 / 6) sinc, the angle is degree C!

(1) From the sine theorem, there is a + B = √ 2C
And because a + B + C = √ 2 + 1
So C = 1 = ab
(2) Because s = (1 / 6) sinc
So (1 / 2) AB = 1 / 6
So AB = 1 / 3
From (1) there is a + B = √ 2
So cos C = (A & sup2; + B & sup2; - C & sup2;) / 2Ab = 1 / 2
So C = 30 degrees

What are the markers of English present perfect tense, past tense and general present tense?
It's better to be comprehensive and have other tenses

The present tense
often,usually,always,sometimes,never,seldom,every week/day/year/month...,once a week,on Sundays
Past tense
Ago, yesterday, the day before yesterday, last week / year / night / month..., in 1989, just now, at the age of five, one day, ago, long ago, once upon a time, then, on that day,
Present continuous tense
now,at this time,these days,Listen!Look!at this moment/time
Past continuous tense
At this time yesterday, at that time or "when + general past tense clause", at 1:00 last night
The present perfect tense
Recently, recent years, these days / years, lately, since, for + period, in the past few years, ever since, in the last five months, up to now, since then, so far, ever, never, yet, lately, once, twice, three / four times..., already, before, just
Past perfect tense
before,by the end of last year/term/month...
Future tense
tomorrow,next day/week/month/year...,soon,in a few minutes,by...,the day after tomorrow,in the future
Past future tense
the next day/morning/year...,
the following month/week...

Find the rule 2,3,5,8,13, (), (), 55

2+3=5
3+5=8
8+5=13
8+13=21……

Be in a hurry
Find the analytic formula of F (a) = | α | + | β |, where the two heels of the equation x 2 - 2x + 1-4a = 0 are α and β
Please understand

X^2-2X+1-4a=0
===>X=1±2√a
analysis:
When a ≥ 1 / 4,
Then α = 1 + 2 √ a, β = 1-2 √ a
===>f(a)=|α|+|β|=1+2√a+1-2√a=2
When 0 ≤ AF (a) = | α | + | β | = 1 + 2 √ a + 2 √ A-1 = 4 √ a
When AF (a) = | α | + | β | = 1 + 2I √ (- a) + 1-2i √ (- a) = 2
When a

What is the difference between meaning and definition?

I greet the toothy sleeping flowers and their pollinators
Then I held her hand tightly
They say, all of a sudden,
And then disappear into the fog of animals
I enter the central crystal nest, star factory, world window, the end of the sky
Granddaughter forever you ha ha

Which is followed by singular or plural in attributive clause? When to use plural and singular in clause?

1. Replace the singular or plural of the above in the non restrictive attributive clause
2. It is used as interrogative pronoun in question and connective pronoun in noun clause
3. If the antecedent of the non restrictive attributive clause does not refer to the content of the main sentence, but refers to the specific person, time and place, then which is not used
That's right