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Let for two distinct values of p the lines y = x + p touch the ellipse E: fracx^24^2 + fracy^23^2 = 1 at the points A and B. Let the line y = x intersect E at the points C and D. Then the area of the quadrilateral ABCD is equal to

Solution & Explanation

### Related Formula The condition for a line y = mx + p to be tangent to an ellipse fracx^2a^2 + fracy^2b^2 = 1 is: p^2 = a^2m^2 + b^2 The coordinate of the point of contact is given by left(-fraca^2mp, fracb^2pright). ### Core Logic Given the ellipse parameter values a^2 = 16 and b^2 = 9, and tangent line slope m = 1: p^2 = 16(1)^2 + 9 = 25 implies p = pm 5 Thus, the two values of p are 5 and -5. The points of contact A and B are: - For p = 5: A = left(-frac16(1)5, frac95right) = left(-frac165, frac95right) - For p = -5: B = left(-frac16(1)-5, frac9-5right) = left(frac165, -frac95right) ### Step 1: Intersecting line with Ellipse The line y = x intersects the ellipse fracx^216 + fracy^29 = 1: fracx^216 + fracx^29 = 1 implies frac25x^2144 = 1 implies x^2 = frac14425 implies x = pm frac125 Since y = x, the intersection points C and D are: C = left(-frac125, -frac125right) quad textand quad D = left(frac125, frac125right) ### Step 2: Calculating Quadrilateral Area The area of quadrilateral ABCD with vertices mapped symmetrically can be computed using the standard coordinate determinant matrix layout formula: textArea = frac12 beginvmatrix x_A & y_A & 1 \\ x_B & y_B & 1 \\ x_C & y_C & 1 endvmatrix + dots = 24 ### Pattern Recognition Notice that the tangent lines are parallel and symmetric (p = pm 5), and the intersecting line passes through the origin. This symmetry creates a geometric parallelogram, simplifying your area calculation by doubling the area of triangle ABD. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Conic Sections

Reference Study Guides

More Conic Sections Previous-Year Questions — Page 3

Q73 2025 Hyperbola
Consider the hyperbola fracx^2a^2 -fracy^2b^2 = 1 having one of its focus at mathrmP(-3,0) . If the latus rectum through its other focus subtends a right angle at mathrmP and a^2 b^2 = alpha sqrt2 -beta ,alpha ,beta in mathbbN , calculate alpha + beta.
Numerical Answer. Answer: 1944 to 1944

Solution

### Related Formula For a standard hyperbola: - Focus positions are (pm ae, 0). - Length of semi-latus rectum is fracb^2a. - Eccentricity identity linkage: b^2 = a^2(e^2 - 1) implies a^2e^2 = a^2 + b^2. ### Core Logic Given focus F_1 equiv (-ae, 0) equiv P(-3, 0), so ae = 3. The other focus is F_2 equiv (ae, 0) equiv (3, 0). The latus rectum passes vertically through F_2, with endpoints L_1left(ae, fracb^2aright) and L_2left(ae, -fracb^2aright). This segment subtends a right angle at P(-ae, 0). By symmetry, the top half angle at P must be exactly 45^circ. ### Step 1: Set Up Slope Relationship
Hyperbola diagram for Q73 - JEE Main 2025 Morning
Hyperbola diagram for Q73 - JEE Main 2025 Morning
Using the geometric slope relationship: tan 45^circ = fractextheighttextbase = fracb^2/a2ae 1 = fracb^22a^2e implies 2a^2e = b^2 implies b^2 = 6a quad (textsince ae = 3) ### Step 2: Solve the Quadratic Excentricity Equation Substitute ae = 3 and b^2 = 6a into the eccentricity identity a^2e^2 = a^2 + b^2: 9 = a^2 + 6a implies a^2 + 6a - 9 = 0 Solving for a using the quadratic formula (taking the positive root since a > 0): a = frac-6 pm sqrt36 - 4(1)(-9)2 = frac-6 + sqrt722 = -3 + 3sqrt2 = 3(sqrt2 - 1) ### Step 3: Evaluate product and sum coefficients Now compute a^2b^2: a^2b^2 = a^2(6a) = 6a^3 6a^3 = 6left[3(sqrt2 - 1)right]^3 = 6 times 27 times (sqrt2 - 1)^3 6a^3 = 162 times (2sqrt2 - 6 + 3sqrt2 - 1) = 162 times (5sqrt2 - 7) 6a^3 = 810sqrt2 - 1134 Matching with alphasqrt2 - beta gives: alpha = 810 quad textand quad beta = 1134 Calculate the final required sum: alpha + beta = 810 + 1134 = 1944 ### Pattern Recognition Recognizing that the right angle subtended at the opposite focus implies a perfect tan(45^circ) right triangle instantly yields the key linear constraint b^2 = 2a(ae), avoiding the need for lengthy distance-formula tracking. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Conic Sections
Q60 2025 Ellipse and Focal Distances
Let the ellipse 3x^2 + py^2 = 4 pass through the centre C of the circle x^2 + y^2 - 2x - 4y - 11 = 0 of radius r. Let f_1, f_2 be the focal distances of the point C on the ellipse. Then 6f_1f_2 - r is equal to
  • A. 74
  • B. 68
  • C. 70
  • D. 78

Solution

### Related Formula textFocal Distance Product on Vertical Ellipse = b^2 - e^2 k^2 ### Core Logic Extract the coordinate center of the target circle, substitute it directly to locate the missing parameter p, and resolve eccentricity metrics. ### Step 1: Extract Circle Metric Values For circle x^2 + y^2 - 2x - 4y - 11 = 0: textCentre C(1, 2), quad textRadius r = sqrt1 + 4 + 11 = 4 ### Step 2: Standardize Ellipse Formulation Ellipse passes through point C(1,2): 3(1)^2 + p(2)^2 = 4 implies 3 + 4p = 4 implies p = frac14 Standard model form: fracx^24/3 + fracy^216 = 1 (b > a, vertical configuration axis). e = sqrt1 - frac4/316 = sqrt1 - frac112 = sqrtfrac1112 ### Step 3: Evaluate Product Chain Focal distance elements at ordinate coordinate height k=2 are bounded by b pm ek: f_1 f_2 = b^2 - e^2 k^2 = 16 - left(frac1112right) times 4 = 16 - frac113 = frac373 Target evaluation expression response string: 6f_1 f_2 - r = 6 left(frac373right) - 4 = 74 - 4 = 70 ### Pattern Recognition Pay attention to whether b > a or a > b when analyzing ellipse forms. Focal distance definitions swap directions immediately across major horizontal/vertical configurations. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Conic Sections Class 11 Mathematics: Circles
Q75 2025 Tangent to Parabola and Circle Properties
Let r be the radius of the circle, which touches x -axis at point (a, 0) , a < 0 and the parabola y^2 = 9x at the point (4, 6) . Then r is equal to
Numerical Answer. Answer: 30 to 30

Solution

### Related Formula textTangent line at point (x_1, y_1) implies yy_1 = 2a(x+x_1) ### Core Logic Establish the tangent vector expression at the parabola intersection mark. Since this path line functions as a shared contact tangent boundaries sheet for the circular arc, impose radius equations. ### Step 1: Derive Shared Parabola Tangent Line Tangent line profile for y^2 = 9x at coordinate indicator (4,6): 6y = 9 cdot left( fracx+42 right) implies 3x - 4y + 12 = 0 ### Step 2: Build Geometric Metric Connections Circle touches axis at (a,0), mapping coordinates center directly to C(a,r). Perpendicular boundary constraint steps require: frac3a - 4r + 125 = pm r implies 3a + 12 = 4r pm 5r ### Step 3: Solve for Radius Matrix Bounds Enforce circle equation intersection constraint profile (x-a)^2 + (y-r)^2 = r^2 at point (4,6): a^2 - 8a - 12r + 52 = 0 Evaluating the target systems from structural logic tracks rejects positive value parameters, providing: a = -14, quad r = 30 {{SOL_IMG_75}} ### Pattern Recognition Shared tangent elements connect independent conic fields. Locating circular center boundaries using axial coordinate tracking simplifies secondary equations. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Conic Sections Class 11 Mathematics: Circles
Q59 2025 Chord with a Given Midpoint
If alpha x + beta y = 109 is the equation of the chord of the ellipse fracx^29 +fracy^24 = 1, whose mid point is left(frac52,frac12right), then alpha +beta is equal to
  • A. 37
  • B. 46
  • C. 58
  • D. 72

Solution

### Related Formula Equation of a chord of a conic section with a given midpoint (x_1, y_1) is: T = S_1 ### Core Logic Given midpoint Mleft(frac52, frac12 ight) and ellipse fracx^29 + fracy^24 = 1.
Chord with a Given Midpoint diagram for Q59 - JEE Main 2025 Evening
Chord with a Given Midpoint diagram for Q59 - JEE Main 2025 Evening
Write T and S_1 terms: T: fracxleft(frac52right)9 + fracyleft(frac12right)4 S_1: fracleft(frac52right)^29 + fracleft(frac12right)^24 Equating both sides: frac5x18 + fracy8 = frac2536 + frac116 ### Step 1: Simplify to Standard Form Multiply the entire equation by 144 to eliminate fractions: 144left(frac5x18right) + 144left(fracy8right) = 144left(frac2536right) + 144left(frac116right) 40x + 18y = 4(25) + 9(1) 40x + 18y = 109 Comparing this directly with alpha x + beta y = 109 provides: alpha = 40, quad beta = 18 alpha + beta = 40 + 18 = 58 ### Pattern Recognition Whenever you see 'chord whose midpoint is given', write T = S_1 automatically. Match coefficients directly at the final step after equating constant integers. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Conic Sections
Q75 2025 Properties of Focal Chords
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. Answer: 1328 to 1328

Solution

### 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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