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Tangents are drawn to ellipse (x^2)/(a^2...

Tangents are drawn to ellipse `(x^2)/(a^2) + (y^2)/(b^2) = 1` at points `P(theta_1)` and `Q (theta_2)` then the point of intersection of these tangents is

A

`(("acos"(theta_1 + theta_2)/(2))/("cos"(theta_1 - theta_2)/2), ("b sin" (theta_1 + theta_2)/(2))/("cos"(theta_1 - theta_2)/2))`

B

`(("acos"(theta_1 - theta_2)/(2))/("cos"(theta_1 + theta_2)/2), ("b sin" (theta_1 - theta_2)/(2))/("cos"(theta_1 + theta_2)/2))`

C

`(("a sin"(theta_1 + theta_2)/(2))/("sin"(theta_1 - theta_2)/2), ("b cos" (theta_1 + theta_2)/(2))/("sin"(theta_1 - theta_2)/2))`

D

none

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The correct Answer is:
To find the point of intersection of the tangents drawn to the ellipse \(\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1\) at points \(P(\theta_1)\) and \(Q(\theta_2)\), we can follow these steps: ### Step 1: Write the equations of the tangents The equations of the tangents at points \(P(\theta_1)\) and \(Q(\theta_2)\) on the ellipse are given by: 1. For point \(P(\theta_1)\): \[ \frac{x}{a \cos \theta_1} + \frac{y}{b \sin \theta_1} = 1 \] 2. For point \(Q(\theta_2)\): \[ \frac{x}{a \cos \theta_2} + \frac{y}{b \sin \theta_2} = 1 \] ### Step 2: Set up the equations We can rewrite these equations as: 1. \(b \sin \theta_1 x + a \cos \theta_1 y = ab\) (Equation 1) 2. \(b \sin \theta_2 x + a \cos \theta_2 y = ab\) (Equation 2) ### Step 3: Eliminate \(y\) To find the intersection point, we can eliminate \(y\) by manipulating these equations. We can multiply Equation 1 by \(\sin \theta_2\) and Equation 2 by \(\sin \theta_1\): 1. \(b \sin \theta_1 \sin \theta_2 x + a \cos \theta_1 \sin \theta_2 y = ab \sin \theta_2\) 2. \(b \sin \theta_2 \sin \theta_1 x + a \cos \theta_2 \sin \theta_1 y = ab \sin \theta_1\) Now, subtract the second equation from the first: \[ (b \sin \theta_1 \sin \theta_2 - b \sin \theta_2 \sin \theta_1)x + (a \cos \theta_1 \sin \theta_2 - a \cos \theta_2 \sin \theta_1)y = ab(\sin \theta_2 - \sin \theta_1) \] ### Step 4: Simplify the equation The left-hand side simplifies to: \[ 0x + (a \cos \theta_1 \sin \theta_2 - a \cos \theta_2 \sin \theta_1)y = ab(\sin \theta_2 - \sin \theta_1) \] This means we can express \(y\) in terms of \(x\): \[ y = \frac{ab(\sin \theta_2 - \sin \theta_1)}{a(\cos \theta_1 \sin \theta_2 - \cos \theta_2 \sin \theta_1)} \] ### Step 5: Find \(x\) and \(y\) coordinates Now, we can find the \(x\) coordinate by substituting back into either of the tangent equations. For example, substituting into Equation 1: \[ x = \frac{ab(\sin \theta_2 - \sin \theta_1)}{b \sin \theta_1 \cos \theta_2 - b \sin \theta_2 \cos \theta_1} \] ### Step 6: Final coordinates of intersection Thus, the point of intersection of the tangents is given by: \[ \left( \frac{a(\sin \theta_1 + \sin \theta_2)}{\sin(\theta_2 - \theta_1)}, \frac{b(\sin \theta_1 + \sin \theta_2)}{\sin(\theta_2 - \theta_1)} \right) \]
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ML KHANNA-THE ELLIPSE-PROBLEM SET (2) (Multiple Choice Questions)
  1. The locus of the mid-points of the portion of the tangents to the elli...

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  2. Tangents are drawn to x^2 + 3y^2 = 2. The locus" of mid-point of inter...

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  3. Tangents are drawn to ellipse (x^2)/(a^2) + (y^2)/(b^2) = 1 at points ...

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  4. The locus of the point of intersection of tangents to an ellipse at tw...

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  5. The eccentric angles of extremities of a chord of an ellipse (x^2)/(a^...

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  6. The tangent at a point P(acosvarphi,bsinvarphi) of the ellipse (x^2)/(...

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  7. If the line x+2y+4=0 cutting the ellipse (x^(2))/(a^(2))+(y^(2))/(b^(2...

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  8. If P Q R is an equilateral triangle inscribed in the auxiliary circle ...

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  9. On the ellipse 4x^(2)+9y^(2)=1, the points at which the tangent are pa...

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  10. Tangents are drawn to the ellipse 3x^2 + 5y^2 = 32 and 25x^2 +9y^2 = 4...

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  11. Let two perpendicular chords of the ellipse (x^2)/(a^2) + (y^2)/(b^2) ...

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  12. An ellipse passes through the point (4,-1) and touches the line x+4...

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  13. Locus of mid-point of the focal chord of ellipse (x^(2))/(a^(2))+(y^(...

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  14. The normal at a variable point P on the ellipse (x^2)/(a^2)+(y^2)/(b^2...

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  15. If P(theta1) and D(theta2) be the end, points of two semi-conjugate di...

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  16. If CP and CD are semi-conjugate diameters of the ellipse x^(2)/a^(2) +...

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  17. CP and CD are conjugate semi-diameters of the ellipse x^(2)/a^(2) + y^...

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  18. The maximum distance of the centre of the ellipse (x^(2))/(16) +(y^(2)...

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  19. Tangents are drawn from the point P(3,4) to the ellipse x^(2)/9+y^(2)/...

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  20. Tangents are drawn from the point P(3, 4) to the ellipse x^2/9 +y^2/4 ...

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