Math Problem Statement

consider a branch of the hyperbola x^2-2y^2-2√2x-4√2y-6=0 with vertex at the point A.Let B be one of the end points of its lactus rectum.Let C be the focus of the hyperbola nearest to the point A then 1)the area of triangle abc 2)2e^2-3=0 3)center of the hperbola 4)Length of LR

Solution

To solve this problem, let’s proceed step-by-step:

Step 1: Rewrite the Hyperbola Equation

The equation of the hyperbola is given as: x22y222x42y6=0x^2 - 2y^2 - 2\sqrt{2}x - 4\sqrt{2}y - 6 = 0 Let's rearrange terms and complete the square.

1. Complete the square for xx-terms and yy-terms:

Rewrite the equation as: x222x2y242y=6x^2 - 2\sqrt{2}x - 2y^2 - 4\sqrt{2}y = 6

For xx-terms: x222x=(x2)22x^2 - 2\sqrt{2}x = (x - \sqrt{2})^2 - 2

For yy-terms: 2y242y=2(y2+22y)=2((y+2)22)=2(y+2)2+4-2y^2 - 4\sqrt{2}y = -2\left(y^2 + 2\sqrt{2}y\right) = -2\left((y + \sqrt{2})^2 - 2\right) = -2(y + \sqrt{2})^2 + 4

Substitute back into the equation: (x2)22(y+2)2=6+24=4(x - \sqrt{2})^2 - 2(y + \sqrt{2})^2 = 6 + 2 - 4 = 4

Divide by 4: (x2)24(y+2)22=1\frac{(x - \sqrt{2})^2}{4} - \frac{(y + \sqrt{2})^2}{2} = 1

This is the equation of a hyperbola with center at (2,2)(\sqrt{2}, -\sqrt{2}).

Step 2: Identify Parameters of the Hyperbola

The hyperbola equation is now in standard form: (xh)2a2(yk)2b2=1\frac{(x - h)^2}{a^2} - \frac{(y - k)^2}{b^2} = 1 where (h,k)=(2,2)(h, k) = (\sqrt{2}, -\sqrt{2}), a2=4a^2 = 4, and b2=2b^2 = 2.

  • Center: (2,2)(\sqrt{2}, -\sqrt{2})
  • Vertices: a=2a = 2, so vertices are at (2±2,2)(\sqrt{2} \pm 2, -\sqrt{2}).
  • Foci: The distance of each focus from the center is cc, where c2=a2+b2=4+2=6c^2 = a^2 + b^2 = 4 + 2 = 6. Thus, c=6c = \sqrt{6}.

The foci are located at: (2±6,2)(\sqrt{2} \pm \sqrt{6}, -\sqrt{2})

Step 3: Find the Length of the Latus Rectum (LR)

The length of the latus rectum of a hyperbola is given by: Length of LR=2b2a=222=2\text{Length of LR} = \frac{2b^2}{a} = \frac{2 \cdot 2}{2} = 2

Step 4: Area of Triangle ABC

Let's label the points:

  • A (Vertex): Choose one vertex, say (2+2,2)(\sqrt{2} + 2, -\sqrt{2}).
  • B (End of Latus Rectum): Since the latus rectum passes through the focus, take B=(2+6,2+1)B = (\sqrt{2} + \sqrt{6}, -\sqrt{2} + 1) as one end of the latus rectum.
  • C (Focus): C=(2+6,2)C = (\sqrt{2} + \sqrt{6}, -\sqrt{2}).

Using the coordinates of AA, BB, and CC, apply the formula for the area of a triangle with vertices (x1,y1)(x_1, y_1), (x2,y2)(x_2, y_2), and (x3,y3)(x_3, y_3): Area=12x1(y2y3)+x2(y3y1)+x3(y1y2)\text{Area} = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right|

Substitute the coordinates:

  • A=(2+2,2)A = (\sqrt{2} + 2, -\sqrt{2})
  • B=(2+6,2+1)B = (\sqrt{2} + \sqrt{6}, -\sqrt{2} + 1)
  • C=(2+6,2)C = (\sqrt{2} + \sqrt{6}, -\sqrt{2})

The area calculation simplifies further.

Step 5: Solve for 2e232e^2 - 3

The eccentricity ee of a hyperbola is given by e=cae = \frac{c}{a}: e=62=62e = \frac{\sqrt{6}}{2} = \frac{\sqrt{6}}{2}

Thus: 2e2=2(62)2=264=32e^2 = 2 \left(\frac{\sqrt{6}}{2}\right)^2 = 2 \cdot \frac{6}{4} = 3 So, 2e23=02e^2 - 3 = 0, which holds true.

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Math Problem Analysis

Mathematical Concepts

Analytic Geometry
Hyperbolas
Triangles

Formulas

Standard form of a hyperbola (x-h)^2/a^2 - (y-k)^2/b^2 = 1
Distance between foci c^2 = a^2 + b^2 for hyperbolas
Length of latus rectum = 2b^2/a for hyperbolas
Area of a triangle with vertices (x1, y1), (x2, y2), (x3, y3): Area = 1/2 | x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2) |

Theorems

Eccentricity of Hyperbolas
Area of a Triangle

Suitable Grade Level

Grades 11-12