Let L be a tangent line to the hyperbola x y = 2 at x = 9 . Find the area of the triangle bounded by L and the coordinate axes. ( Give your answer as a whole or exact number.)

Respuesta :

Answer:

[tex]A = 4[/tex]

Step-by-step explanation:

The equation of the slope of the tangent line L is obtained by deriving the equation of the hyperbola:

[tex]y = \frac{2}{x}[/tex]

[tex]y'=-2\cdot x^{-2}[/tex]

The numerical value of the slope is:

[tex]y' = -2 \cdot (9)^{-2}\\y' = -\frac{2}{81}[/tex]

The component of the y-axis is:

[tex]y = \frac{2}{9}[/tex]

Now, the tangent line has the following mathematical model:

[tex]y = m \cdot x + b[/tex]

The value of the intercept is found by isolating it within the equation and replacing all known variables:

[tex]b = y - m \cdot x[/tex]

[tex]b = \frac{2}{9}-(-\frac{2}{81} )\cdot (9)\\b = \frac{4}{9}[/tex]

Thus, the tangent line is:

[tex]y = -\frac{2}{81}\cdot x + \frac{4}{9}[/tex]

The vertical distance between a point of the tangent line and the origin is given by the intercept.

[tex]d_{y} = \frac{4}{9}[/tex]

In order to find horizontal distance between a point of the tangent line and the origin, let equalize y to zero and clear x:

[tex]-\frac{2}{81}\cdot x + \frac{4}{9}=0[/tex]

[tex]-\frac{2}{9}\cdot x + 4 = 0[/tex]

[tex]x = 18[/tex]

[tex]d_{x} = 18[/tex]

The area of the triangle is computed by this formula:

[tex]A = \frac{1}{2}\cdot d_{x}\cdot d_{y}[/tex]

[tex]A = \frac{1}{2}\cdot (18)\cdot (\frac{4}{9} )[/tex]

[tex]A = 4[/tex]

The Area of triangle bounded by line and coordinate axes is 4 square unit.

Equation of Tangent line:

Given equation of hyperbola is, [tex]xy=2[/tex]

If x = 9. Then [tex]y=2/x=2/9[/tex]

Slope of tangent line,

          [tex]\frac{dy}{dx} =-\frac{2}{x^{2} } =-\frac{2}{81}[/tex]

Equation of line is,

            [tex]y-\frac{2}{9} =-\frac{2}{81}(x-9)\\ \\y=-\frac{2}{81}x+\frac{4}{9}[/tex]

y- intercept is, [tex]y=\frac{4}{9}[/tex] and x- intercept, [tex]x=18[/tex]

Area of triangle bounded by line and coordinate axes is,

           [tex]A=\frac{1}{2}*18*\frac{4}{9} \\\\Area=4[/tex]

Learn more about the Hyperbola here:

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