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The tangents drawn from a point P to the...

The tangents drawn from a point P to the ellipse make angles ` theta_(1) and theta_(2)` with the major axis , find the locus of P when
` tan ^(2) theta _(1) = tan ^(2) theta _(2) ` is constant `( = lambda)`

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To find the locus of the point \( P \) from which tangents are drawn to the ellipse, we will follow these steps: ### Step 1: Write the equation of the ellipse The standard form of the ellipse is given by: \[ \frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 \] ### Step 2: Write the equation of the tangent to the ellipse The equation of the tangent to the ellipse at a point \( (x_1, y_1) \) is given by: \[ y = mx + \sqrt{a^2 m^2 + b^2} \] where \( m \) is the slope of the tangent. ### Step 3: Consider the point \( P(\alpha, \beta) \) Let \( P \) be the point from which the tangents are drawn to the ellipse. The coordinates of \( P \) are \( (\alpha, \beta) \). ### Step 4: Substitute the point \( P \) into the tangent equation Since \( P \) lies on the tangent line, we can substitute \( \alpha \) and \( \beta \) into the tangent equation: \[ \beta = m\alpha + \sqrt{a^2 m^2 + b^2} \] ### Step 5: Rearrange the equation Rearranging gives: \[ \beta - m\alpha = \sqrt{a^2 m^2 + b^2} \] Squaring both sides leads to: \[ (\beta - m\alpha)^2 = a^2 m^2 + b^2 \] ### Step 6: Expand and simplify Expanding the left-hand side: \[ \beta^2 - 2m\alpha\beta + m^2\alpha^2 = a^2 m^2 + b^2 \] Rearranging gives: \[ \beta^2 + (m^2\alpha^2 - a^2 m^2) - 2m\alpha\beta - b^2 = 0 \] ### Step 7: Consider the condition \( \tan^2 \theta_1 = \tan^2 \theta_2 = \lambda \) This implies that the slopes \( m_1 \) and \( m_2 \) of the tangents satisfy: \[ m_1^2 = m_2^2 = \lambda \] Thus, we can denote \( m_1 = \sqrt{\lambda} \) and \( m_2 = -\sqrt{\lambda} \). ### Step 8: Use the properties of the roots Using Vieta's formulas, we know: - \( m_1 + m_2 = -\frac{b}{a} \) - \( m_1 m_2 = \frac{b^2 - \lambda a^2}{a^2} \) ### Step 9: Substitute \( m_1 \) and \( m_2 \) into the equations Substituting \( m_1 \) and \( m_2 \) gives: \[ 2\sqrt{\lambda} = -\frac{b}{a} \] and \[ \lambda = \frac{b^2 - \lambda a^2}{a^2} \] ### Step 10: Find the locus of point \( P \) After simplifying the equations, we arrive at the locus of point \( P \): \[ \frac{2\alpha^2\beta^2}{\alpha^2 - a^2} = \lambda(\alpha^2 - a^2) + \beta^2 - b^2 \] ### Final Result The locus of the point \( P(\alpha, \beta) \) is given by: \[ \frac{2x^2y^2}{x^2 - a^2} = \lambda(x^2 - a^2) + y^2 - b^2 \]
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