Let y^2 = 12x the parabola and S be its focus. Let PQ be a focal chord of the parabola such that (SP) (SQ) = frac1474. Let C be the circle described taking PQ as a diameter. If the equation of a circle C is 64x^2 + 64y^2 - alpha x - 64sqrt3y = beta, then \beta - \alpha is equal to

Numerical Answer Type:
Enter a numerical value Answer: 1328 to 1328 +4 marks

Solution & Explanation

### Related Formula Properties of focal chord parameter metrics in parabolas y^2 = 4ax: t_1 cdot t_2 = -1 Distance to the directrix property: SP = a(1 + t^2), quad SQ = aleft(1 + frac1t^2right) ### Core Logic Given parabola y^2 = 12x implies a = 3. Focus S = (3, 0). Set up focal segments product equation: SP cdot SQ = 3(1+t^2) cdot 3left(1+frac1t^2right) = frac1474 9 cdot frac(1+t^2)^2t^2 = frac1474 implies frac(1+t^2)^2t^2 = frac4912 Solving for t^2: 12t^4 - 25t^2 + 12 = 0 implies t^2 = frac34 quad textor quad frac43 ### Step 1: Compute Endpoint Coordinate Bounds Choosing t = -fracsqrt32 allows defining both chord coordinates symmetrically: P(3t^2, 6t) implies Pleft(frac94, -3sqrt3right) Qleft(frac3t^2, -frac6tright) implies Q(4, 4sqrt3) ### Step 2: Derive Circle Equation Write the diameter circle form equation: (x - 4)left(x - frac94right) + (y - 4sqrt3)(y + 3sqrt3) = 0 x^2 + y^2 - frac254x - sqrt3y - 27 = 0 Multiply by 64 to clear the fractions and match the given equation template structure: 64x^2 + 64y^2 - 400x - 64sqrt3y - 1728 = 0 Comparing directly with 64x^2 + 64y^2 - alpha x - 64sqrt3y = beta yields: alpha = 400, quad beta = 1728 beta - alpha = 1728 - 400 = 1328 ### Pattern Recognition The distance from focal chord endpoints to the focus equals their perpendicular distance to the directrix. This property connects parameter metrics to geometric lengths cleanly. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Conic Sections Class 11 Mathematics: Circles

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Q27 jee_main_2024_31_jan_morning Ellipse and Hyperbola Properties
Let the foci and length of the latus rectum of an ellipse fracx^2a^2 + fracy^2b^2 = 1, a > b be (pm 5, 0) and sqrt50, respectively. Then, the square of the eccentricity of the hyperbola fracx^2b^2 - fracy^2a^2 b^2 = 1 equals
Numerical Answer. Answer: 51 to 51

Solution

### Core Logic For the ellipse, foci are at (pm 5, 0) implies ae = 5. Latus rectum = frac2b^2a = sqrt50 = 5sqrt2 implies b^2 = frac5sqrt2a2. ### Step 1: Solve for a and b Using b^2 = a^2(1 - e^2): a^2 - (ae)^2 = b^2 implies a^2 - 25 = frac5sqrt2a2 2a^2 - 5sqrt2a - 50 = 0 2a^2 - 10sqrt2a + 5sqrt2a - 50 = 0 2a(a - 5sqrt2) + 5sqrt2(a - 5sqrt2) = 0 a = 5sqrt2 (since a > 0). Now, b^2 = frac5sqrt2(5sqrt2)2 = 25 implies b = 5. ### Step 2: Hyperbola Eccentricity The hyperbola is fracx^2b^2 - fracy^2a^2b^2 = 1. Here, semi-major axis A = b and semi-minor axis B = ab. Using eccentricity formula for hyperbola e_H^2 = 1 + fracB^2A^2: e_H^2 = 1 + fraca^2 b^2b^2 = 1 + a^2 Since a = 5sqrt2, a^2 = 50. e_H^2 = 1 + 50 = 51 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Conic Sections

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