Equation of two diameters of a circle are 2x-3y=5 and 3x-4y=7. The line joining the points (-(22)/(7),-4) and (-(1)/(7),3) intersects the circle at only one point P(α,β). Then 17β-α is equal to

Numerical Answer Type:
Enter a numerical value Answer: 2 to 2 +4 marks

Solution & Explanation

Related Formula

The intersection of any two non-parallel diameters yields the center of the circle. A line that intersects a circle at exactly one point is a tangent line. The tangent at the point of contact P is always perpendicular to the radius CP, thus mtangent × mradius = -1.

Core Logic

Find the center C by solving the two diameter equations:

2x - 3y = 5 (1) 3x - 4y = 7 (2)

Multiply (1) by 3 and (2) by 2: 6x - 9y = 15 6x - 8y = 14 Subtracting the equations gives -y = 1 ⇒ y = -1. Substitute y = -1 into (1): 2x + 3 = 5 ⇒ 2x = 2 ⇒ x = 1. Center C is (1, -1).

Find the equation of the line joining A(-(22)/(7), -4) and B(-(1)/(7), 3). Slope of AB: mAB = (3 - (-4))/(-1/7 - (-22/7)) = (7)/(21/7) = (7)/(3). Equation of line AB:

y - 3 = (7)/(3)(x + (1)/(7))

3y - 9 = 7x + 1

7x - 3y + 10 = 0 (Line AB)

Tangents and Normal
Tangents and Normal

Step 1: Exploit Tangency Geometry

Since line AB intersects the circle at only one point P(α, β), line AB is a tangent to the circle, and P is the point of tangency. The radius line CP is perpendicular to tangent AB. Slope of CP (mCP) must be -(3)/(7).

Equation of the line passing through center C(1, -1) with slope -(3)/(7):

y - (-1) = -(3)/(7)(x - 1) 7y + 7 = -3x + 3 3x + 7y + 4 = 0 (Line CP)
Step 2: Solve for Intersection P

Point P(α, β) is the intersection of Tangent AB and Radius CP. Solve the system:

7x - 3y = -10 (× 7) 3x + 7y = -4 (× 3)

49x - 21y = -70 9x + 21y = -12 Add them: 58x = -82 ⇒ x = -(82)/(58) = -(41)/(29). So, α = -(41)/(29).

Substitute x into 3x + 7y = -4:

3(-(41)/(29)) + 7y = -4 -(123)/(29) + 7y = -(116)/(29)

7y = (123 - 116)/(29) = (7)/(29) ⇒ y = (1)/(29)$. So, $β = (1)/(29)$.

Step 3: Evaluate Target Expression

Evaluate $17β - α$:

17\left(\frac{1}{29}\right) - \left(-\frac{41}{29}\right) = \frac{17 + 41}{29} = \frac{58}{29} = 2$$
Pattern Recognition

When a line "intersects a circle at exactly one point", it's a coded cue to stop thinking about quadratics and discriminants, and immediately build a perpendicular geometric radius from the center to find the exact tangency coordinate.

Chapter Mix

Class 11 Mathematics: Circles Class 11 Mathematics: Straight Lines

Reference Study Guides

More Circles Previous-Year Questions — Page 3

Q11 jee_main_2026_22_january_evening Hyperbola Properties and Area of Triangle
Let P(10, 2√(15)) be a point on the hyperbola (x²)/(a²) - (y²)/(b²) = 1, whose foci are S and S'. If the length of its latus rectum is 8, then the square of the area of Δ PSS' is equal to:
  • A. 4200
  • B. 900
  • C. 1462
  • D. 2700

Solution

Related Formula

Latus rectum length = (2b²)/(a) = 8 b² = 4a. Focal length = 2ae = 2√(a² + b²).

Core Logic

Substitute P(10, 2√(15)) and b² = 4a into hyperbola equation:

(100)/(a²) - (60)/(4a) = 1 a² + 15a - 100 = 0 (a + 20)(a - 5) = 0 a = 5 (a > 0)

Thus, b² = 20 b = √(20).

Step 1: Calculate Focal Distance and Area

Focal distance SS' = 2ae = 2 √(a² + b²) = 2 √(25 + 20) = 6√(5). Area of Δ PSS' = (1)/(2) × base × height = (1)/(2) (6√(5)) (2√(15)) = 30√(3) = A.

Step 2: Square of Area
A² = (30√(3))² = 900 × 3 = 2700
Pattern Recognition

Use latus rectum relation to reduce hyperbola parameter to single variable quadratic.

Chapter Mix

Class 11 Maths: Conic Sections

Q16 jee_main_2026_22_january_evening Ellipse Focal Distances
Let S and S' be the foci of the ellipse (x²)/(25) + (y²)/(9) = 1 and P(α, β) be a point on the ellipse in the first quadrant. If (SP)² + (S'P)² - SP · S'P = 37, then α² + β² is equal to:
  • A. 15
  • B. 11
  • C. 17
  • D. 13

Solution

Related Formula

For ellipse (x²)/(a²) + (y²)/(b²) = 1: SP + S'P = 2a = 10, e = √(1 - b²/a²) = √(1 - 9/25) = 4/5. Focal distances: SP = a - eα = 5 - (4)/(5)α, S'P = a + eα = 5 + (4)/(5)α.

Core Logic

Using algebraic identity:

(SP + S'P)² - 3 SP · S'P = 37 100 - 3 SP · S'P = 37 SP · S'P = 21

Substitute focal distance formula:

25 - (16)/(25)α² = 21 (16)/(25)α² = 4 α² = (25)/(4)
Step 1: Calculate beta^2 and Sum

Substitute α² into ellipse equation (α²)/(25) + (β²)/(9) = 1:

(1)/(4) + (β²)/(9) = 1 β² = (27)/(4) α² + β² = (25)/(4) + (27)/(4) = (52)/(4) = 13
Pattern Recognition

Express (SP)² + (S'P)² - SP · S'P in terms of (SP+S'P) to determine SP · S'P instantly.

Chapter Mix

Class 11 Maths: Conic Sections

Q17 jee_main_2026_22_january_evening Locus of Midpoint of Chord
Let the locus of the mid-point of the chord through the origin O of the parabola y² = 4x be the curve S. Let P be any point on S. Then the locus of the point, which internally divides OP in the ratio 3:1, is:
  • A. 3y² = 2x
  • B. 2y² = 3x
  • C. 3x² = 2y
  • D. 2x² = 3y

Solution

Related Formula

Section formula for internal division in ratio m:n:

R(h,k) = ( (m x₂ + n x₁)/(m+n), (m y₂ + n y₁)/(m+n) )
Core Logic

Locus of midpoint diagram for Q17 - JEE Main 2026 Evening
Locus of midpoint diagram for Q17 - JEE Main 2026 Evening

Let chord endpoint be Q(t², 2t). Midpoint M(h,k) of OQ:

h = (t²)/(2), k = t k² = 2h

So curve S is y² = 2x.

Now P lies on S: y² = 2x, so P = ((t²)/(2), t). Point R(h,k) divides OP in ratio 3:1:

Step 1: Section Formula Application

Locus of midpoint diagram for Q17 - JEE Main 2026 Evening
Locus of midpoint diagram for Q17 - JEE Main 2026 Evening

h = (3(t²/2) + 0)/(4) = (3t²)/(8), k = (3(t) + 0)/(4) = (3t)/(4)

From k = (3t)/(4) t = (4k)/(3). Substitute into h:

h = (3)/(8) ((4k)/(3))² = (3)/(8) · (16k²)/(9) = (2k²)/(3) 2k² = 3h 2y² = 3x
Pattern Recognition

Parametrize midpoint curve S, then re-apply section ratio to derive final locus equation.

Chapter Mix

Class 11 Maths: Conic Sections

Q1 jee_main_2026_23_january_morning Hyperbola
Let the domain of the function f(x) = ₃ ₅ ₇(9x - x² - 13) be the interval (m, n). Let the hyperbola (x²)/(a²) - (y²)/(b²) = 1 have eccentricity (n)/(3) and the length of the latus rectum (8m)/(3). Then b² - a² is equal to:
  • A. 5
  • B. 11
  • C. 9
  • D. 7

Solution

Related Formula
e = √(1 + (b²)/(a²)) L.R. = (2b²)/(a)
Core Logic

For the domain of the given logarithmic function, the argument of the innermost logarithm must be strictly greater than 1 because of the nested logs:

₅( ₇(9x-x²-13))>0 ⇒ ₇(9x-x²-13) > 1 ⇒ 9x-x²-13 > 7 ⇒ x²-9x+20 < 0 ⇒ (x-4)(x-5) < 0

Thus, 4 < x < 5. Therefore, the domain interval is (4, 5), yielding m = 4 and n = 5.

Step 1: Hyperbola Properties

Given eccentricity e = (n)/(3) = (5)/(3):

e = √(1 + (b²)/(a²)) = (5)/(3) ⇒ (b²)/(a²) = (25)/(9) - 1 = (16)/(9) ⇒ (b)/(a) = (4)/(3)

Given the length of the latus rectum is (8m)/(3):

(2b²)/(a) = (8(4))/(3) = (32)/(3) ⇒ 2b((b)/(a)) = (32)/(3) ⇒ 2b((4)/(3)) = (32)/(3) ⇒ 8b = 32 ⇒ b = 4

Since (b)/(a) = (4)/(3), we get a = 3.

Step 2: Final Calculation

We need to find b² - a²:

b² - a² = (4)² - (3)² = 16 - 9 = 7
Pattern Recognition

Nested logarithmic domains require unpacking from the outside in: ₐ(X) > 0 ⇒ X > 1. Linking function domains to coordinate geometry parameters is a standard JEE cross-topic pattern.

Chapter Mix

Class 11 Maths: Conic Sections Class 11 Maths: Relations and Functions

Q5 jee_main_2026_23_january_morning Ellipse
Let the line y - x = 1 intersect the ellipse (x²)/(2) + (y²)/(1) = 1 at the points A and B. Then the angle made by the line segment AB at the center of the ellipse is:
  • A. π - ⁻¹((1)/(4))
  • B. (π)/(2) + ⁻¹((1)/(4))
  • C. (π)/(2) + 2 ⁻¹((1)/(4))
  • D. (π)/(2) - ⁻¹((1)/(4))

Solution

Related Formula
θ = | (m₁ - m₂)/(1 + m₁ m₂) |
Core Logic

Find the intersection points of the line y = x + 1 and the ellipse (x²)/(2) + y² = 1.

Ellipse diagram for Q5 - JEE Main 2026 Morning
Ellipse diagram for Q5 - JEE Main 2026 Morning
Substitute y = x + 1 into the ellipse equation:

(x²)/(2) + (x + 1)² = 1 x² + 2(x² + 2x + 1) = 2 3x² + 4x = 0 ⇒ x(3x + 4) = 0

This gives x = 0 or x = -(4)/(3).

Step 1: Calculate Intersection Points

For x = 0, y = 1 ⇒ A(0, 1). For x = -(4)/(3), y = -(4)/(3) + 1 = -(1)/(3) ⇒ B(-(4)/(3), -(1)/(3)).

Ellipse diagram for Q5 - JEE Main 2026 Morning
Ellipse diagram for Q5 - JEE Main 2026 Morning

Step 2: Find Angle at the Origin

Let O(0,0) be the center of the ellipse. The angle made by segment AB at O is ∠ AOB. The slope of OA is m₁ = (1 - 0)/(0 - 0) = ∞ (which means OA is along the y-axis, angle is π/2). The slope of OB is m₂ = (-1/3 - 0)/(-4/3 - 0) = (1)/(4). The angle of OB with the positive x-axis is θ = ⁻¹((1)/(4)). The total angle ∠ AOB is (π)/(2) + θ = (π)/(2) + ⁻¹((1)/(4)).

Pattern Recognition

When solving line-conic intersection, explicit extraction of points (A, B) is often simpler than using homogenization if the intersection yields simple rational or integer coordinates.

Chapter Mix

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

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