JEE Main · Mathematics ↓ Falling

Straight Lines appeared 29 times across 3 years — 3.4% of Mathematics. This question is from Area of Triangles and Inscribed Shapes.

Year 2026 2025 2024 Total
Questions 7 13 9 29

Let the line x + y = 1 meet the axes of x and y at A and B, respectively. A right angled triangle AMN is inscribed in the triangle OAB, where O is the origin and the points M and N lie on the lines OB and AB, respectively. If the area of the triangle AMN is (4)/(9) of the area of the triangle OAB and AN: NB = \lambda : 1, then the sum of all possible value(s) of λ is :

Solution & Explanation

Related Formula

Area of a right-angled triangle:

Area = (1)/(2) × base × height
Core Logic

The line equation is x + y = 1, giving intercept coordinates A(1, 0) and B(0, 1).

Area of Triangles and Inscribed Shapes diagram for Q58 - JEE Main 2025 Evening
Area of Triangles and Inscribed Shapes diagram for Q58 - JEE Main 2025 Evening

Area of Δ OAB = (1)/(2) × 1 × 1 = (1)/(2). Given area condition:

Area of Δ AMN = (4)/(9) × (1)/(2) = (2)/(9)
Step 1: Set up Trigonometric Tracing

Let ∠ MAO = 45^° - θ. Since Δ OAB is isosceles right-angled at O, ∠ OAB = 45^°. This establishes:

OA = 1, AM = (45^° - θ) AN = (45^° - θ) θ MN = (45^° - θ) θ
Step 2: Solve for Angles and Ratios
Area(Δ AMN) = (1)/(2) × ²(45^° - θ) θ θ = (2)/(9)

Solving the trigonometric ratio yields:

θ = 2 or (1)/(2)

Rejecting θ = 2 based on physical boundaries within the triangle limits:

(AN)/(NB) = (λ)/(1) = θ = 2

Thus, the valid evaluation matches the option sequence value of 2.

Pattern Recognition

When dealing with inscribed right triangles inside symmetric linear bounds, parameterizing coordinates with angles matching the axis slope simplifies configuration variables dramatically.

Chapter Mix

Class 11 Mathematics: Straight Lines

Reference Study Guides

More Straight Lines Previous-Year Questions — Page 5

Q jee_main_2024_29_january_evening Distance of a Point From a Line
The distance of the point (2, 3) from the line 2x - 3y + 28 = 0, measured parallel to the line √(3) x - y + 1 = 0, is equal to
  • A. 4√(2)
  • B. 6√(3)
  • C. 3 + 4√(2)
  • D. 4 + 6√(3)

Solution

Related Formula
x = x₁ + r θ, y = y₁ + r θ
Core Logic

The line is measured parallel to √(3)x - y + 1 = 0, which has a slope θ = √(3) θ = 60^°. Thus, θ = (1)/(2) and θ = √(3)2.

Writing any point P along this direction passing through (2,3) in parametric coordinates:

P = (2 + r 60^°, 3 + r 60^°) = (2 + (r)/(2), 3 + √(3)r2)
Step 1: Finding Intersection Point

Since P must lie on the given line 2x - 3y + 28 = 0:

2(2 + (r)/(2)) - 3(3 + √(3)r2) + 28 = 0 4 + r - 9 - 3√(3)r2 + 28 = 0 23 + r(1 - 3√(3)2) = 0 r( 3√(3) - 22) = 23 r = 463√(3) - 2

Rationalizing the denominator:

r = 46(3√(3) + 2)(3√(3))² - 2² = 46(3√(3) + 2)27 - 4 = 46(3√(3) + 2)23 = 2(3√(3) + 2) = 4 + 6√(3)
Pattern Recognition

Distance measured parallel to a given direction is always resolved most efficiently using parametric equations of lines rather than perpendicular metrics.

Chapter Mix

Class 11 Mathematics: Straight Lines

Q jee_main_2024_29_january_evening Intersection of Lines and Distance
Let A be the point of intersection of the lines 3x + 2y = 14, 5x - y = 6 and B be the point of intersection of the lines 4x + 3y = 8, 6x + y = 5. The distance of the point P(5, -2) from the line AB is
  • A. (13)/(2)
  • B. 8
  • C. (5)/(2)
  • D. 6

Solution

Related Formula
Perpendicular distance d = |ax₀ + by₀ + c|√(a² + b²)
Core Logic

Let us find coordinates of point A by solving:

  • 3x + 2y = 14
  • 5x - y = 6 y = 5x - 6
  • Substituting y in equation 1:

3x + 2(5x - 6) = 14 13x - 12 = 14 13x = 26 x = 2 y = 5(2) - 6 = 4 A = (2, 4)

Let us find coordinates of point B by solving:

  • 4x + 3y = 8
  • 6x + y = 5 y = 5 - 6x
  • Substituting y in equation 3:

4x + 3(5 - 6x) = 8 4x + 15 - 18x = 8 -14x = -7 x = (1)/(2) y = 5 - 6((1)/(2)) = 2 B = ((1)/(2), 2)
Step 1: Equation of line AB
Slope m = (4 - 2)/(2 - 1/2) = (2)/(3/2) = (4)/(3)

Equation of line AB:

y - 4 = (4)/(3)(x - 2) 3y - 12 = 4x - 8 4x - 3y + 4 = 0
Step 2: Distance Estimation

Perpendicular distance from point P(5, -2) to line 4x - 3y + 4 = 0:

d = |4(5) - 3(-2) + 4|√(4² + (-3)²) = |20 + 6 + 4|√(25) = (30)/(5) = 6
Pattern Recognition

Verify calculation metrics step-by-step. Finding straight intersections correctly upfront avoids scaling mistakes down the track.

Chapter Mix

Class 11 Mathematics: Straight Lines

Q jee_main_2024_27_jan_morning Angle Between Two Lines
The portion of the line 4x+5y=20 in the first quadrant is trisected by the lines L₁ and L₂ passing through the origin. The tangent of an angle between the lines L₁ and L₂ is:
  • A. (8)/(5)
  • B. (25)/(41)
  • C. (2)/(5)
  • D. (30)/(41)

Solution

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

Find the intercepts of the line 4x + 5y = 20 in the first quadrant. Put y=0 ⇒ x=5. Point X(5, 0). Put x=0 ⇒ y=4. Point Y(0, 4). The line segment XY is trisected by two points, say A and B. Point A divides YX in the ratio 2:1, and B divides it in 1:2.

Step 1: Trisection Points Calculation

Using the section formula for A (closer to Y-axis, ratio 1:2 from Y to X):

A = ( (1(5) + 2(0))/(3), (1(0) + 2(4))/(3) ) = ( (5)/(3), (8)/(3) )

Using the section formula for B (closer to X-axis, ratio 2:1 from Y to X):

B = ( (2(5) + 1(0))/(3), (2(0) + 1(4))/(3) ) = ( (10)/(3), (4)/(3) )
Step 2: Finding Line Slopes

The lines L₁ and L₂ pass through the origin (0,0) to points A and B. Slope of OA (m₁):

m₁ = (8/3 - 0)/(5/3 - 0) = (8)/(5)

Slope of OB (m₂):

m₂ = (4/3 - 0)/(10/3 - 0) = (4)/(10) = (2)/(5)
Step 3: Calculating Tangent of the Angle

Substitute the slopes into the angle formula:

θ = | (8/5 - 2/5)/(1 + (8/5)(2/5)) | θ = (6/5)/(1 + 16/25) θ = (6/5)/((25+16)/25) = (6/5)/(41/25) θ = (6)/(5) × (25)/(41) = (30)/(41)
Pattern Recognition

For trisection or specific division of an intercepted segment, identify the axis intercepts first, rapidly apply the internal section formula, compute origin-centered slopes (which equal just the y/x ratio of the points), and pass them into the tan formula.

Chapter Mix

Class 11 Maths: Straight Lines

Q7 jee_main_2024_29_jan_morning Angle Bisector and Reflection
In a Δ ABC, suppose y=x is the equation of the bisector of the angle B and the equation of the side AC is 2x-y=2. If 2AB=BC and the point A and B are respectively (4,6) and (α,β), then α+2β is equal to
  • A. 42
  • B. 39
  • C. 48
  • D. 45

Solution

Related Formula

Image of a point (x₁, y₁) across line y=x is (y₁, x₁).

Angle Bisector Theorem: The angle bisector of a triangle divides the opposite side into segments proportional to the lengths of the adjacent sides:

(AB)/(BC) = (AD)/(DC)
Core Logic

Given A(4,6) and Angle bisector of B is y=x. Because y=x bisects angle B, the geometric reflection of vertex A across the bisector line y=x must lie exactly on the line containing the side BC. Let the reflection of A(4,6) be A'. Across y=x, the coordinates swap: A' = (6,4)

Next, find the intersection point D of the bisector y=x and side AC (2x-y=2). Substitute y=x into 2x-y=2:

2x - x = 2 ⇒ x = 2 ⇒ y = 2

So, point D is (2,2).

Angle Bisector and Reflection
Angle Bisector and Reflection

Step 1: Utilize Section Formula

By the internal angle bisector theorem:

(AD)/(DC) = (AB)/(BC)

Given 2AB = BC, so (AB)/(BC) = (1)/(2). This means point D(2,2) divides the segment AC in the ratio 1:2. Let C have coordinates (xc, yc). Applying the section formula for D(2,2) dividing A(4,6) and C(xc, yc) in ratio 1:2:

2 = (1 · xc + 2 · 4)/(1 + 2) ⇒ 6 = xc + 8 ⇒ xc = -2 2 = (1 · yc + 2 · 6)/(1 + 2) ⇒ 6 = yc + 12 ⇒ yc = -6

So, C is (-2,-6).

Step 2: Find Equation of BC

The line BC passes through point C(-2,-6) and the reflection point A'(6,4). Find the slope of BC:

mBC = (4 - (-6))/(6 - (-2)) = (10)/(8) = (5)/(4)

Equation of BC:

y - 4 = (5)/(4)(x - 6) 4y - 16 = 5x - 30 5x - 4y - 14 = 0
Step 3: Solve for Vertex B

Vertex B(α, β) is the intersection of line BC and the angle bisector y=x. Substitute y=x into 5x - 4y - 14 = 0:

5x - 4x - 14 = 0 ⇒ x = 14

Thus, y = 14. Therefore, B is (14, 14), implying α = 14 and β = 14.

Calculate α + 2β:

α + 2β = 14 + 2(14) = 42
Pattern Recognition

Reflection properties drastically simplify angle bisector questions. If you know the bisector equation, reflecting one vertex over it gives a coordinate on the opposing extended ray. This paired with the angle bisector proportion theorem locks the entire geometric frame.

Chapter Mix

Class 11 Mathematics: Straight Lines

Q7 jee_main_2024_30_january_evening Angle Bisectors
If x² - y² + 2hxy + 2gx + 2fy + c = 0 is the locus of a point, which moves such that it is always equidistant from the lines x + 2y + 7 = 0 and 2x - y + 8 = 0 , then the value of g + c + h - f equals
  • A. 14
  • B. 6
  • C. 8
  • D. 29

Solution

Related Formula
Distance of (x, y) from ax+by+c=0 is d = |ax + by + c|√(a² + b²)
Core Logic

The locus of a point P(x, y) equidistant from lines x + 2y + 7 = 0 and 2x - y + 8 = 0 is the pair of angle bisectors:

|x + 2y + 7|√(1² + 2²) = |2x - y + 8|√(2² + (-1)²) x + 2y + 7√(5) = ± 2x - y + 8√(5)
Step 1: Generating the Combined Equation

Squaring both sides eliminates the ± and generates the combined equation of the bisectors:

(x + 2y + 7)² - (2x - y + 8)² = 0

Using a² - b² = (a - b)(a + b):

[ (x + 2y + 7) - (2x - y + 8) ] [ (x + 2y + 7) + (2x - y + 8) ] = 0 (-x + 3y - 1)(3x + y + 15) = 0 (x - 3y + 1)(3x + y + 15) = 0
Step 2: Expanding the Equation

Multiply out the terms:

3x² + xy + 15x - 9xy - 3y² - 45y + 3x + y + 15 = 0 3x² - 3y² - 8xy + 18x - 44y + 15 = 0
Step 3: Comparing Coefficients

The standard form given is x² - y² + 2hxy + 2gx + 2fy + c = 0. Divide our derived equation by 3 to match the leading coefficients:

x² - y² - (8)/(3)xy + 6x - (44)/(3)y + 5 = 0

Now, compare coefficients:

2h = -(8)/(3) ⇒ h = -(4)/(3) 2g = 6 ⇒ g = 3 2f = -(44)/(3) ⇒ f = -(22)/(3)

c = 5

Step 4: Final Calculation

Substitute into the expression g + c + h - f:

3 + 5 - (4)/(3) - (-(22)/(3)) = 8 + (18)/(3) = 8 + 6 = 14
Pattern Recognition

Locus of equidistant points from two lines is their pair of angle bisectors. Equating squares d₁² = d₂² directly yields the joint equation of bisectors without needing explicit line separation.

Chapter Mix

Class 11 Maths: Straight Lines

More Straight Lines Questions — jee_main_2025_29_jan_evening

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