If the minor axis length is root 5 and the eccentricity is two-thirds, the two focal points of the ellipse are F1 and F2. If the ellipse crosses a and B, the circumference of the triangle abf2 is?

If the minor axis length is root 5 and the eccentricity is two-thirds, the two focal points of the ellipse are F1 and F2. If the ellipse crosses a and B, the circumference of the triangle abf2 is?

The minor axis is the root 5
Then B = root 5
c/a=2/3
Obviously a = 3, C = 2
The circumference of triangle abf2 is AF1 + af2 + BF2 + BF1 = 4A = 12
This uses the definition of ellipse
There's something you don't understand
If the minor axis is radical 5, then the minor half axis B = √ 5 / 2
Centrifugation e = C / a = 2 / 3 square to get C & # 178 / A & # 178; = (A & # 178; - B & # 178;) / A & # 178; = 1 - (5 / 4) / A & # 178; = 4 / 9
The solution is a = 3 / 2
Triangle abf2 perimeter = AB + af2 + BF2
=(AF1 + BF1) + (af2 + BF2) (the sum of distances from a point on the ellipse to two focal points is 2a)
=2a+2a
=... unfold
If the minor axis is radical 5, then the minor half axis B = √ 5 / 2
Centrifugation e = C / a = 2 / 3 square to get C & # 178 / A & # 178; = (A & # 178; - B & # 178;) / A & # 178; = 1 - (5 / 4) / A & # 178; = 4 / 9
The solution is a = 3 / 2
Triangle abf2 perimeter = AB + af2 + BF2
=(AF1 + BF1) + (af2 + BF2) (the sum of distances from a point on the ellipse to two focal points is 2a)
=2a+2a
=4*(3/2)
=6
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B = root 5 / 2
e=c/a=2/3∴c=（2/3）a
According to B & # 178; + C & # 178; = A & # 178; a = 3 / 2 is obtained
Then according to the definition of ellipse: the sum of the distances from one point to two focal points on the ellipse is 2a, we can get C △ abf2 = 4A = 6
The two focal points of the ellipse with short axis length of 5 and eccentricity of 23 are F1 and F2 respectively. If the ellipse is crossed by a straight line through F1 at two points a and B, the perimeter of △ abf2 is ()
A. 24B. 12C. 6D. 3
From the meaning B = 52, e = CA = 23, A2 = B2 + C2, a = 32, 4A = 6, so C
The standard equation of an ellipse with the ratio of X to the second power of 9 plus the ratio of y to the second power of 4 equal to 1, and the eccentricity is 5 to 5
In ellipse X & # 178 / 9 + Y & # 178 / 4 = 1, a & # 178; = 9, B & # 178; = 4, C & # 178; = 5
If the eccentricity e = √ 5 / 5 = C / a = √ 5 / A, then a = 5, C = C = √ 5, then B & # 178; = A & # 178; - C & # 178; = 20, then:
x²/25＋y²/20=1
X²/9+Y²/4=1
e=c/a=1/√5
The title meaning is not clear, cannot calculate!
If the eccentricity of the ellipse with focus on the y-axis is equal to 1, then the value of the real number m is?
If the eccentricity of the ellipse with focus on the y-axis is equal to 1, then the value of the real number m is?
The ellipse with focus on the y-axis is 5 / x ^ 2 + m / y square equal to 1
M>5
a^2=m a=√m
b^2=5
c^2=a^2-b^2 c=√(m-5)
e=c/a=(√(m-5))/(√m)=√2/2
(m-5)/m=1/2
2m-10=m
m=10
If the equation x2 + ky2 = k represents an ellipse with focus on the y-axis, then the value range of the real number k is
If K < 1, divide both sides of the equation by K at the same time, you can see that
If a (π / 2, π) is known, then the curve represented by the equation x & sup2; sina-y & sup2; Sina = cosa is?
x^2tana-y^2tana=1
Because a belongs to π / 2, π
So Tana
It is known that y = (K-3) x + K & # 178; - 9 is a positive proportional function of X. when x = - 4, find the value of Y
Because it's a positive scale function, so
K & # 178; - 9 = 0, so k = 3 or K = - 3
Because K-3 is not equal to 0
So k = 3 is rounded off, which means k = - 3
So the function is y = - 6x
When x = - 4, y = 24
If the eccentricity e of hyperbola x24 + Y2K = 1 ∈ (1,2), then the value range of K is______ .
The eccentricity of hyperbola x24 + Y2K = 1, e ∈ (1,2), ｜ 1 ＜ 4 − K2 ＜ 2, the solution is - 12 ＜ K ＜ 0. So the answer is: - 12 ＜ K ＜ 0
If two of the quadratic equations x2-ax + B = 0 are Sina and cosa, then the trajectory equation of point P (a, b) is obtained
According to Weida's theorem:
a=sina+cosa
b=sinacosa
sin²a+cos²a=1=(sina+cosa)²-2sinacosa=a²-2b
a²-2b=1
b=(a²-1)/2
This is the trajectory equation of point P, which is a parabola
If y = KX + (K + 4) is a positive proportional function, then K=______ When y = - 12, X=______
When k = - 4, y = - 12, x = 3
PS: the definition of positive scale function
If y = KX (k is constant and K is not equal to 0), y is called the positive proportion function of X