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Conic Sections · Question 63

JEE Main 2025 (Online) 7th April Evening ShiftMCQEasy📈 Topic in 61% papers+4−1
1

Let p be the number of all triangles that can be formed by joining the vertices of a regular polygon P of n sides and q be the number of all quadrilaterals that can be formed by joining the vertices of P. If p + q = 126, then the eccentricity of the ellipse x216 + y2n = 1 is :

  1. 1 2
  2. 12
  3. 74
  4. 34

Answer

(1) 1 2

Solution

No three vertices of a regular polygon are collinear, so

p = nC3 and q = nC4

p + q = nC3 + nC4 = n+1C4 = 126

9C4 = 126, n + 1 = 9 n = 8

Ellipse: x216 + y28 = 1, with a2 = 16, b2 = 8

e = 1 - b2a2 = 1 - 816 = 1 2

Answer: (1)

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2

Let the lengths of the transverse and conjugate axes of a hyperbola in standard form be 2a and 2b, respectively, and one focus and the corresponding directrix of this hyperbola be (-5, 0) and 5x + 9 = 0, respectively. If the product of the focal distances of a point ( , 2 5) on the hyperbola is p, then 4p is equal to .

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3

The length of the latus-rectum of the ellipse, whose foci are (2, 5) and (2, -3) and eccentricity is 45, is

  1. 503
  2. 185
  3. 65
  4. 103
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4

Let C be the circle x2 + (y - 1)2 = 2, E1 and E2 be two ellipses whose centres lie at the origin and major axes lie on x-axis and y-axis respectively. Let the straight line x + y = 3 touch the curves C, E1 and E2 at P(x1, y1), Q(x2, y2) and R(x3, y3) respectively. Given that P is the mid point of the line segment QR and PQ = 2 23, the value of 9(x1y1 + x2y2 + x3y3) is equal to .

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5

Let the sum of the focal distances of the point P(4, 3) on the hyperbola H: x2a2 - y2b2 = 1 be 8 53. If for H, the length of the latus rectum is l and the product of the focal distances of the point P is m, then 9l2 + 6m is equal to :

  1. 187
  2. 184
  3. 186
  4. 185
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6

Let for two distinct values of p the lines y = x + p touch the ellipse E: x242 + y232 = 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 :

  1. 48
  2. 20
  3. 24
  4. 36
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7

The centre of a circle C is at the centre of the ellipse E: x2a2 + y2b2 = 1, a > b. Let C pass through the foci F1 and F2 of E such that the circle C and the ellipse E intersect at four points. Let P be one of these four points. If the area of the triangle PF1F2 is 30 and the length of the major axis of E is 17, then the distance between the foci of E is :

  1. 12
  2. 26
  3. 13
  4. 132
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8

The axis of a parabola is the line y=x and its vertex and focus are in the first quadrant at distances 2 and 2 2 units from the origin, respectively. If the point (1, k) lies on the parabola, then a possible value of k is :

  1. 8
  2. 3
  3. 9
  4. 4
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9

The radius of the smallest circle which touches the parabolas y = x2 + 2 and x = y2 + 2 is

  1. 7 216
  2. 7 28
  3. 7 22
  4. 7 24
JEE Main 2025 (Online) 3rd April Morning Shift
10

A line passing through the point P( 5, 5) intersects the ellipse x236 + y225 = 1 at A and B such that (PA) (PB) is maximum. Then 5 (PA2 + PB2 ) is equal to :

  1. 290
  2. 377
  3. 338
  4. 218
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11

Let the product of the focal distances of the point P(4, 2 3) on the hyperbola H: x2a2 - y2b2 = 1 be 32. Let the length of the conjugate axis of H be p and the length of its latus rectum be q. Then p2 + q2 is equal to

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