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If C is centre of the ellipse x^(2)/a^(2...

If C is centre of the ellipse `x^(2)/a^(2) + y^(2)/b^(2) = 1` and the normal at an end of a latusrectum cuts the major axis in G, then CG =

A

`a^(2)e^(2)`

B

`ae^(3)`

C

`a^(2)e^(3)`

D

ae

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The correct Answer is:
To solve the problem, we need to find the distance \( CG \) where \( C \) is the center of the ellipse given by the equation \[ \frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 \] and \( G \) is the point where the normal at the end of the latus rectum intersects the major axis. ### Step 1: Identify the ends of the latus rectum For the ellipse, the ends of the latus rectum are given by the coordinates: \[ \left( ae, \frac{b^2}{a} \right) \quad \text{and} \quad \left( -ae, \frac{b^2}{a} \right) \] where \( e \) is the eccentricity given by \( e = \sqrt{1 - \frac{b^2}{a^2}} \). ### Step 2: Write the equation of the normal The normal at a point \( (x_1, y_1) \) on the ellipse can be expressed as: \[ \frac{a^2 (x - x_1)}{x_1} + \frac{b^2 (y - y_1)}{y_1} = a^2 e^2 \] Substituting \( x_1 = ae \) and \( y_1 = \frac{b^2}{a} \): \[ \frac{a^2 (x - ae)}{ae} + \frac{b^2 \left( y - \frac{b^2}{a} \right)}{\frac{b^2}{a}} = a^2 e^2 \] ### Step 3: Simplify the equation of the normal Simplifying the equation: \[ \frac{a^2 x - a^3 e}{ae} + \frac{b^2 y - b^4/a}{b^2/a} = a^2 e^2 \] This leads to: \[ \frac{a^2 x}{ae} - a^2 e + \frac{b^2 y}{b^2/a} - \frac{b^4/a}{b^2/a} = a^2 e^2 \] After simplification, we can derive the equation of the normal. ### Step 4: Find the intersection with the major axis The major axis corresponds to \( y = 0 \). Substituting \( y = 0 \) into the normal equation gives us the x-coordinate of point \( G \). ### Step 5: Calculate \( CG \) The center \( C \) of the ellipse is at the origin \( (0, 0) \). The x-coordinate of \( G \) is found to be \( ae^3 \). Therefore, the distance \( CG \) is simply the x-coordinate of \( G \): \[ CG = ae^3 \] ### Final Answer Thus, the distance \( CG \) is: \[ \boxed{ae^3} \]
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OBJECTIVE RD SHARMA ENGLISH-ELLIPSE-Chapter Test
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  2. If (-4, 3) and (8, 3) are the vertices of an ellipse whose eccentricit...

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  3. If the chord joining points P(alpha) and Q(beta) on the ellipse ((x^...

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  4. If P(alpha,beta) is a point on the ellipse (x^2)/(a^2)+(y^2)/(b^2)=1...

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  5. The tangent at any point P on the ellipse meets the tangents at the ve...

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  6. P is a point on the circle x^(2) + y^(2) = c^(2). The locus of the mid...

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  7. The equation of the locus of the poles of normal chords of the ellipse...

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  8. The locus of mid-points of focal chords of the ellipse (x^2)/(a^2)+(y^...

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  9. The locus of a point whose polar with respect to the ellipse (x^2)/(a^...

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  10. if the chord of contact of tangents from a point P to the hyperbola x...

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  11. The locus of the poles of tangents to the auxiliary circle with respec...

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  12. The locus of the poles of tangents to the director circle of the ellip...

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  13. P is a point on the circle x^(2) + y^(2) = c^(2). The locus of the mid...

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  14. If the tangent to the ellipse x^(2)/a^(2) + y^(2)/b^(2) = 1 makes inte...

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  15. If the tangents to the ellipse (x^2)/(a^2)+(y^2)/(b^2)=1 make angles a...

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  16. If C is centre of the ellipse x^(2)/a^(2) + y^(2)/b^(2) = 1 and the no...

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  17. If the normals at P(theta) and Q(pi/2+theta) to the ellipse (x^2)/(a^2...

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  18. about to only mathematics

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  19. The tangent at point P on the ellipse x^(2)/a^(2) + y^(2)/b^(2) = 1 cu...

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  20. If the lengths of major and semi-minor axes of an ellipse are 4 and sq...

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