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Conic Sections appeared 94 times across 3 years — 10.9% of Mathematics. This question is from Parabola Equation with Given Vertex and Directrix.

Year 2026 2025 2024 Total
Questions 29 44 21 94

If the equation of the parabola with vertex V((3)/(2),3) and the directrix x+2y=0 is α x²+β y²-γ xy-30x-60y+225=0, then α+β+γ is equal to:

Solution & Explanation

Related Formula

The locus definition of a parabola states that the squared distance from any point P(x,y) to the focus S(x₀, y₀) equals the squared perpendicular distance to the directrix line Ax + By + C = 0:

(x - x₀)² + (y - y₀)² = ((Ax + By + C)²)/(A² + By²)
Step 1: Determine the Focus coordinates

The axis line of the parabola is perpendicular to the directrix x + 2y = 0 and passes through the vertex V(1.5, 3). Slope of directrix = -0.5 ⇒ Slope of axis = 2.

Equation of axis :

y - 3 = 2(x - (3)/(2)) ⇒ y - 2x = 0

The intersection of the axis (y - 2x = 0) and directrix (x + 2y = 0) gives the foot of the directrix, which is (0, 0).

Since the vertex is the midpoint between the focus and the foot of the directrix :

((3)/(2), 3) = ((xf + 0)/(2), (yf + 0)/(2)) ⇒ Focus S = (3, 6)
Step 2: Derive the Parabola Locus Equation

Equate the distance equations from point P(x,y) :

(x - 3)² + (y - 6)² = ((x + 2y)²)/(1² + 2²) 5(x² - 6x + 9 + y² - 12y + 36) = x² + 4xy + 4y² 5x² - 30x + 45 + 5y² - 60y + 180 = x² + 4xy + 4y² 4x² + y² - 4xy - 30x - 60y + 225 = 0
Step 3: Coefficient Extraction

Compare with the equation template α x² + β y² - γ xy - 30x - 60y + 225 = 0 :

α = 4, β = 1, γ = 4 α + β + γ = 4 + 1 + 4 = 9
Pattern Recognition

The vertex is always exactly midway between the focus and the foot of the directrix line along the line of symmetry. Finding the origin (0,0) as the foot quickly reveals the focus coordinates via doubling.

Chapter Mix

Class 11 Mathematics: Conic Sections

Reference Study Guides

More Conic Sections Previous-Year Questions

Q11 jee_main_2026_21_jan_morning Coinciding Foci of Ellipse and Hyperbola
Let the foci of hyperbola coincide with the foci of the ellipse (x²)/(36) +(y²)/(16) = 1 . If the eccentricity of the hyperbola is 5, then the length of its latus rectum is:
  • A. 12
  • B. 16
  • C. 96√(5)
  • D. 24√(5)

Solution

Related Formula
Eccentricity of ellipse e₁ = √(1 - (b²)/(a²)) Foci = (± ae₁, 0) Length of Latus Rectum of hyperbola = 2bhyp²ahyp
Core Logic

For the given ellipse (x²)/(36) + (y²)/(16) = 1: a² = 36 ⇒ a = 6 b² = 16

e₁ = √(1 - (16)/(36)) = √(1 - (4)/(9)) = √(5)3

Foci of the ellipse are at (± ae₁, 0) = (± 6 · √(5)3, 0) = (± 2√(5), 0).

Step 1: Establish Hyperbola Parameters

Let the hyperbola be (x²)/(p²) - (y²)/(q²) = 1. Its foci coincide with the ellipse, so the foci of hyperbola are also (± 2√(5), 0). Let e be the eccentricity of the hyperbola. We are given e = 5. Focus of hyperbola is pe = 2√(5).

p(5) = 2√(5) ⇒ p = 2√(5)5 = 2√(5)
Step 2: Find the Conjugate Axis (q)

For the hyperbola:

e² = 1 + (q²)/(p²) 25 = 1 + q²( 2√(5))² 24 = (q²)/(4/5) ⇒ 24 = (5q²)/(4) 5q² = 96 ⇒ q² = (96)/(5)
Step 3: Calculate Latus Rectum

Length of Latus Rectum = (2q²)/(p)

= 2 ((96)/(5)) 2√(5) = (96)/(5) × √(5) = 96√(5)
Pattern Recognition

Co-focal conics share the exact mathematical value of their focal length ae (or pe). Instantly extract c = ae from the first shape and map it directly to c = pe for the second.

Chapter Mix

Class 11 Maths: Conic Sections

Q15 jee_main_2026_21_jan_morning Locus of Intersection of Tangents
Let PQ and MN be two straight lines touching the circle x² + y² - 4x - 6y - 3 = 0 at the points A and B respectively. Let O be the centre of the circle and ∠ AOB = π/3 . Then the locus of the point of intersection of the lines PQ and MN is:
  • A. 3(x² + y²) - 18x - 12y + 25 = 0
  • B. x² + y² - 12x - 18y - 25 = 0
  • C. x² + y² - 18x - 12y - 25 = 0
  • D. 3(x² + y²) - 12x - 18y - 25 = 0

Solution

Related Formula

For external tangents from point R forming angle 2θ at the center, the distance d from center to intersection point obeys θ = (r)/(d).

Core Logic

Given circle: x² + y² - 4x - 6y - 3 = 0 Center O = (2, 3) Radius r = √((-2)² + (-3)² - (-3)) = √(4 + 9 + 3) = √(16) = 4.

The tangents PQ and MN intersect at some point R(h, k). The radius vectors OA and OB subtend angle ∠ AOB = (π)/(3) = 60° at the center. The line joining O and R bisects the angle ∠ AOB. Thus, ∠ AOR = 30°.

Step 1: Apply Trigonometric Relations

Circle tangents intersection locus diagram for Q15 - JEE Main 2026 Morning
Circle tangents intersection locus diagram for Q15 - JEE Main 2026 Morning

In the right-angled triangle Δ AOR, OA is the radius (r = 4) and OR is the hypotenuse.

(30°) = (OA)/(OR) = (r)/(OR) √(3)2 = (4)/(OR) ⇒ OR = 8√(3)
Step 2: Construct the Locus Equation

The distance squared between O(2,3) and R(h,k) is OR²:

OR² = (h - 2)² + (k - 3)² = ( 8√(3))² (h - 2)² + (k - 3)² = (64)/(3) h² - 4h + 4 + k² - 6k + 9 = (64)/(3) 3(h² + k² - 4h - 6k + 13) = 64 3h² + 3k² - 12h - 18k + 39 - 64 = 0 3(h² + k²) - 12h - 18k - 25 = 0
Step 3: Generalize the Equation

Replace (h, k) with (x, y) for the general locus:

3(x² + y²) - 12x - 18y - 25 = 0
Pattern Recognition

The locus of the intersection of tangents enclosing a constant angle is simply a concentric circle. Its radius expands by 1/ (α/2) or 1/ (θ) depending on whether the angle is measured at intersection or center.

Chapter Mix

Class 11 Maths: Conic Sections Class 11 Maths: Straight Lines

Q20 jee_main_2026_21_jan_morning Locus of Internal Section Point
Let O be the vertex of the parabola x²=4y and Q be any point on it. Let the locus of the point P, which divides the line segment OQ internally in the ratio 2: 3 be the conic C. Then the equation of the chord of C, which is bisected at the point (1, 2), is:
  • A. 5x-y-3=0
  • B. 4x-5y+6=0
  • C. x-2y + 3 = 0
  • D. 5x-4y+3=0

Solution

Related Formula
Section Formula: P = (m · Q + n · O)/(m + n) Chord bisected at (x₁, y₁) : T = S₁
Core Logic

Given parabola x² = 4y, its vertex O = (0, 0). A general point Q on x² = 4y is (2t, t²). Let P(h, k) divide OQ in ratio 2:3. By section formula:

h = (2(2t) + 3(0))/(5) = (4t)/(5) k = (2(t²) + 3(0))/(5) = (2t²)/(5)

Locus of point dividing parabolic chord for Q20 - JEE Main 2026 Morning
Locus of point dividing parabolic chord for Q20 - JEE Main 2026 Morning

Step 1: Finding the Locus C

From h = (4t)/(5), we get t = (5h)/(4). Substitute into k:

k = (2)/(5) ((5h)/(4))² = (2)/(5) · (25h²)/(16) = (5h²)/(8) 8k = 5h² ⇒ 5x² = 8y

So the conic C is the parabola 5x² = 8y.

Step 2: Chord bisected at a point

We need the equation of the chord of C: 5x² - 8y = 0 bisected at (x₁, y₁) = (1, 2). Use T = S₁. T = 5xx₁ - 4(y + y₁) = 5x(1) - 4(y + 2) = 5x - 4y - 8 S₁ = 5(1)² - 8(2) = 5 - 16 = -11

Equating T and S₁:

5x - 4y - 8 = -11

5x - 4y + 3 = 0

Pattern Recognition

Internal division locus of a vertex chord on standard conic identically scales the conic. Once the child-conic is found, standard mid-point chord protocol (T=S₁) strictly applies algebraically.

Chapter Mix

Class 11 Maths: Parabola Class 11 Maths: Straight Lines

Q4 jee_main_2026_21_jan_evening Ellipse
In the line α x + 4y = √(7), where α in R, touches the ellipse 3x² + 4y² = 1 at the point P in the first quadrant, then one of the focal distances of P is:
  • A. 1√(3) - 12√(11)
  • B. 1√(3) + 12√(5)
  • C. 1√(3) - 12√(5)
  • D. 1√(3) + 12√(7)

Solution

Related Formula
Condition of tangency for ellipse (x²)/(a²) + (y²)/(b²) = 1 is c² = a²m² + b² Focal distance SP = a ± ex Eccentricity e = √(1 - (b²)/(a²))
Core Logic

Ellipse diagram for Q4 - JEE Main 2026 Evening
Ellipse diagram for Q4 - JEE Main 2026 Evening
Identify the slope and intercepts of the line to find α. Use the point of contact formula to locate P(x₁, y₁) and apply focal distance definitions.

Step 1: Determine alpha

Rewrite the ellipse: (x²)/(1/3) + (y²)/(1/4) = 1 a² = (1)/(3), b² = (1)/(4). The line is y = -(α)/(4)x + √(7)4. Using c² = a²m² + b²:

( √(7)4)² = (1)/(3) (-(α)/(4))² + (1)/(4) (7)/(16) = (α²)/(48) + (4)/(16) (3)/(16) = (α²)/(48) α² = 9 α = ± 3

Since P is in the first quadrant, coordinates x, y are positive, so we use the tangent 3x + 4y - √(7) = 0.

Step 2: Find Point of Contact P

The tangent at P(x₁, y₁) is 3xx₁ + 4yy₁ = 1. Comparing this with 3x + 4y = √(7) (divided by √(7) to match constant 1): 3x√(7) + 4y√(7) = 1. Comparing coefficients:

3x₁ = 3√(7) x₁ = 1√(7) 4y₁ = 4√(7) y₁ = 1√(7)

So P = ( 1√(7), 1√(7)).

Step 3: Calculate Focal Distance

Find eccentricity:

e = √(1 - (1/4)/(1/3)) = √(1 - (3)/(4)) = (1)/(2)

The focal distances are a - ex and a + ex. Since a² = 1/3 a = 1/√(3).

SP = a - ex₁ = 1√(3) - (1)/(2)( 1√(7)) = 1√(3) - 12√(7) S'P = a + ex₁ = 1√(3) + (1)/(2)( 1√(7)) = 1√(3) + 12√(7)

Matching with the options, the focal distance is 1√(3) + 12√(7).

Pattern Recognition

For tangency lx+my+n=0 to x²/a² + y²/b² = 1, use a² l² + b² m² = n². Points of contact can be quickly evaluated by comparing T=0 to the normalized tangent equation.

Chapter Mix

Class 11 Maths: Conic Sections

Q5 jee_main_2026_21_jan_evening Parabola
Let y² = 12x be the parabola with its vertex at O. Let P be a point on the parabola and A be a point on the x-axis such that ∠ OPA = 90°. Then the locus of the centroid of such triangles OPA is:
  • A. y² - 6x + 4 = 0
  • B. y² - 9x + 6 = 0
  • C. y² - 2x + 8 = 0
  • D. y² - 4x + 8 = 0

Solution

Related Formula
Centroid G(x,y) = ( (x₁ + x₂ + x₃)/(3), (y₁ + y₂ + y₃)/(3) ) Product of slopes for perpendicular lines m₁ m₂ = -1
Core Logic

Parabola geometry diagram for Q5 - JEE Main 2026 Evening
Parabola geometry diagram for Q5 - JEE Main 2026 Evening
Define coordinates: O(0,0), P(3t², 6t) (since y² = 12x 4a = 12 a=3). Determine the slope of OP and use perpendicularity to find the equation of PA and locate point A on the x-axis.

Step 1: Locate A via Perpendicularity

Slope of OP is mOP = (6t - 0)/(3t² - 0) = (2)/(t). Since ∠ OPA = 90^°, slope of AP is mAP = -(t)/(2). Equation of AP:

y - 6t = -(t)/(2)(x - 3t²)

To find A on the x-axis, put y = 0:

-6t = -(t)/(2)(x - 3t²) 12 = x - 3t² x = 12 + 3t²

So, A is (12 + 3t², 0).

Step 2: Locus of the Centroid

Let the centroid of OPA be G(h, k).

h = (0 + 3t² + (12 + 3t²))/(3) = (6t² + 12)/(3) = 2t² + 4 k = (0 + 6t + 0)/(3) = 2t

From k = 2t t = (k)/(2). Substitute t into the equation for h:

h = 2((k)/(2))² + 4 = (k²)/(2) + 4 2h = k² + 8 k² = 2h - 8

Replacing (h, k) with (x, y), the locus is y² = 2x - 8 y² - 2x + 8 = 0.

Pattern Recognition

For any right-angled configuration involving the origin and axis on a parabola, parametric geometry simplifies equations significantly. Find coordinates O, P, A, set up the centroid algebraic relations, and eliminate parameter t.

Chapter Mix

Class 11 Maths: Conic Sections Class 11 Maths: Straight Lines

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