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In the triangle ABC, the length of edges a and B are two of the equation x2-5x + 2 = 0, and the angle c = 120, then the edge C =?
a. The length of B is two parts of the equation x2-5x + 2 = 0
a+b=5,ab=2
a^2+b^2=(a+b)^2-2ab=25-4=21
The cosine theorem is as follows
c^2=a^2+b^2-2abcosC=21-2*2*cos120=21-4*(-1/2)=23
C = root 23
Find some phrases in English that contain a
a bit of
a lot of
a few
after a while
in a word
as a whole
in a hurry
in a way
as a matter of fact
The numerator and denominator of the fraction 2000 / 1993 add the same natural number at the same time, and then it is 2012 / 2011. What is the natural number added?
Let the natural number added be X
（1993+X）/（2000+X）=2011/2012
2012（1993+X）=2011（2000+X）
4009916+2012X=4022000+2011X
X=12084
Any plus singular or plural
All of them? When is the order? When is the reply?
Generally, any is followed by an odd number
But any of is plural
The function f (x) = x ^ 2-3 / 2x-k has a zero point on (- 1,1), so we can find the value range of K
f(-1)*f(1)
English translation
They are:
Plant flowers, save water, clean streets
Cultivate flowers ,save water ,clean a street
In Δ ABC, the angle c = 90 degrees, AC = BC, Da bisector angle cab intersects BC with D. question: can we determine a point E on AB so that the perimeter of Δ BDE equals the length of AB
Make AF = dB on AB, connect DF, and make the intersection of AB and e of its perpendicular;
Certificate:
The perimeter of Δ BDE = DB + de + EB = AF + EF + EB = ab
This problem has nothing to do with isosceles right angles and bisectors of angles, only when the middle perpendicular does not intersect FB, there is no solution
What is the plural of desk
desks
The solution of inequality ax's square + BX + C ≤ 0 is - 1 ≤ x ≤ 3, and the solution of inequality CX's square + BX + a ≥ 0
The solution of ax ^ 2 + BX + C ≤ 0 is - 1 ≤ x ≤ 3
Then a > 0
And - 1 + 3 = - B / A, - 1 * 3 = C / A
So B = - 2A, C = - 3a
So CX ^ 2 + BX + a ≥ 0
-3ax^2-2ax+a≥0
3ax^2+2ax-a≤0
3x^2+2x-1≤0
(x+1)(3x-1)≤0
So - 1 ≤ x ≤ 1 / 3
If you don't understand, please hi me, I wish you a happy study!
The little boy could clearly tell the difference between pears and apples
=The little boy ___ ___ ___ pears ___ apples
The little boy could distinguish clearly pears from apples.
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