Let a point A lie between the parallel lines L₁$L_{1}$ and L₂$L_{2}$ such that its distances from L₁$L_{1}$ and L₂$L_{2}$ are 6 and 3 units, respectively. Then the area (in sq. units) of the equilateral triangle ABC, where the points B and C lie on the lines L₁$L_{1}$ and L₂$L_{2}$ respectively, is:
A.15√(6)$15\sqrt{6}$
B.27
C.21√(3)$21\sqrt{3}$
D.12√(2)$12\sqrt{2}$
Solution & Explanation
Related Formula
Area of Equilateral Triangle = √(3)4 a²$$\text{Area of Equilateral Triangle} = \frac{\sqrt{3}}{4} a^2$$
Where a$a$ is the side length.
Core Logic
Let the side of the equilateral triangle be a$a$.
Let θ$\theta$ be the angle between the side AC$AC$ and the parallel line L₂$L_2$.
Then, the angle between the side AB$AB$ and the parallel line L₁$L_1$ can be expressed via alternate geometry. Given distances from A$A$ to the lines form right-angled triangles.
Step 1: Set up geometric projections
Equilateral triangle between parallel lines diagram for Q4 - JEE Main 2026 Morning
From vertex C$C$ to line passing through A$A$ parallel to L₁, L₂$L_1, L_2$, the perpendicular distance is 3$3$.
In the right triangle formed, we have:
θ = (3)/(a)$$\sin \theta = \frac{3}{a}$$
Similarly, point B$B$ lies on L₁$L_1$. The perpendicular distance from A$A$ to L₁$L_1$ is 6$6$.
However, combining the overall heights between the parallel lines, the total distance between L₁$L_1$ and L₂$L_2$ is 6 + 3 = 9$6 + 3 = 9$.
The projection of side BC$BC$ (which connects L₁$L_1$ and L₂$L_2$) vertically is 9$9$.
Area of Δ ABC = √(3)4 a²$$\text{Area of } \Delta ABC = \frac{\sqrt{3}}{4} a^2$$= √(3)4 × 84 = 21√(3)$$= \frac{\sqrt{3}}{4} \times 84 = 21\sqrt{3}$$
Pattern Recognition
When a rigid polygon (like an equilateral triangle or square) is wedged between parallel lines, set a base orientation angle θ$\theta$ for one edge and use rotational shifts (e.g., 60° + θ$60^{\circ} + \theta$) to project heights. Expanding the sine addition formula instantly yields the side length.
Chapter Mix
Class 11 Maths: Straight Lines
Class 11 Maths: Trigonometric Functions
Keywords:#area of the equilateral triangle#JEE Main 2026 Morning Q4#Straight Lines JEE Main 2026#Equilateral Triangle Between Parallel Lines JEE Main 2026
More Straight Lines Previous-Year Questions
Q7jee_main_2026_22_january_eveningOrthocenter and Concurrency
Among the statements:
(S1): If A(5,-1)$A(5,-1)$ and B(-2,3)$B(-2,3)$ are two vertices of a triangle, whose orthocentre is (0,0)$(0,0)$, then its third vertex is (-4,-7)$(-4,-7)$ and
(S2): If positive numbers 2a, b, c$2a, b, c$ are three consecutive terms of an A.P., then the lines ax + by + c = 0$ax + by + c = 0$ are concurrent at (2,-2)$(2,-2)$.
A. Only (S1) is correct
B. Only (S2) is correct
C. Both are incorrect
D. Both are correct
Solution
Related Formula
Orthocenter property: Altitude from A$A$ is perpendicular to BC$BC$, Altitude from B$B$ is perpendicular to AC$AC$.
Concurrency of lines: ax+by+c=0$ax+by+c=0$ passes through (x₀, y₀)$(x_0, y_0)$ if ax₀+by₀+c=0$ax_0+by_0+c=0$ holds.
Core Logic
Triangle orthocenter diagram for Q7 - JEE Main 2026 Evening
Statement 1:
Let third vertex be C(h,k)$C(h,k)$ and orthocenter O(0,0)$O(0,0)$.
Slope AO ·$AO \cdot$ Slope BC = -1 ((-1)/(5)) · ((k-3)/(h+2)) = -1 5h - k + 13 = 0$BC = -1 \implies \left(\frac{-1}{5}\right) \cdot \left(\frac{k-3}{h+2}\right) = -1 \implies 5h - k + 13 = 0$
Solving simultaneously gives h = -4, k = -7 C(-4,-7)$h = -4, k = -7 \implies C(-4,-7)$. Statement 1 is correct.
Statement 2:
2a, b, c$2a, b, c$ in A.P. 2b = 2a + c 2a - 2b + c = 0$\implies 2b = 2a + c \implies 2a - 2b + c = 0$.
Comparing with ax + by + c = 0$ax + by + c = 0$ gives x = 2, y = -2$x = 2, y = -2$. Statement 2 is correct.
Step 1: Final Conclusion
Both (S1) and (S2) are correct statements.
Pattern Recognition
Orthocenter coordinates yield perpendicularity conditions via slopes. Concurrency follows directly from linear relation between line coefficients.
Chapter Mix
Class 11 Maths: Straight Lines
Q4jee_main_2026_23_january_morningArea and Distance
A rectangle is formed by the lines x = 0, y = 0, x = 3$x = 0, y = 0, x = 3$ and y = 4$y = 4$. Let the line L$L$ be perpendicular to 3x + y + 6 = 0$3x + y + 6 = 0$ and divide the area of the rectangle into two equal parts. Then the distance of the point ((1)/(2), -5)$\left(\frac{1}{2}, -5\right)$ from the line L$L$ is equal to:
Any line that divides the area of a rectangle into two equal parts must pass through the center of the rectangle.
Area and Distance diagram for Q4 - JEE Main 2026 Morning
The vertices of the rectangle are (0,0)$(0,0)$, (3,0)$(3,0)$, (3,4)$(3,4)$, and (0,4)$(0,4)$. Its center is at ((3)/(2), 2)$\left(\frac{3}{2}, 2\right)$.
Step 1: Equation of Line L
The line L$L$ is perpendicular to 3x + y + 6 = 0$3x + y + 6 = 0$. The slope of this reference line is -3$-3$. Thus, the slope of L$L$ is m = (1)/(3)$m = \frac{1}{3}$.
The equation of L$L$ passing through ((3)/(2), 2)$\left(\frac{3}{2}, 2\right)$ is:
Area bisectors for symmetric geometric figures (rectangles, circles, ellipses) always pass exactly through their geometric center.
Chapter Mix
Class 11 Maths: Straight Lines
Q4jee_main_2026_23_january_eveningProperties of Rhombus
Let A(1, 2)$A(1, 2)$ and C(-3, -6)$C(-3, -6)$ be two diagonally opposite vertices of a rhombus, whose sides AD$AD$ and BC$BC$ are parallel to the line 7x - y = 14$7x - y = 14$. If B(α, β)$B(\alpha, \beta)$ and D(γ, δ)$D(\gamma, \delta)$ are the other two vertices, then |α + β + γ + δ|$|\alpha + \beta + \gamma + \delta|$ is equal to :
A.9$9$
B.3$3$
C.6$6$
D.1$1$
Solution
Related Formula
In a rhombus, diagonals bisect each other. Therefore, the midpoint of diagonal AC$AC$ is the same as the midpoint of diagonal BD$BD$.
Core Logic
Properties of Rhombus diagram for Q4 - JEE Main 2026 Evening
Given the coordinates of vertices A(1, 2)$A(1, 2)$ and C(-3, -6)$C(-3, -6)$, we can find the midpoint O$O$ of the diagonal AC$AC$.
Let the coordinates of B$B$ and D$D$ be (α, β)$(\alpha, \beta)$ and (γ, δ)$(\gamma, \delta)$ respectively. Since the midpoint of BD$BD$ is also (-1, -2)$(-1, -2)$:
The extra information regarding the parallel line 7x - y = 14$7x - y = 14$ is completely redundant for finding the sum of the coordinates. Always check if a basic geometric property (like diagonals bisecting) circumvents heavy calculations.
Chapter Mix
Class 11 Maths: Straight Lines
Q13jee_main_2026_24_january_morningAngle Bisectors of a Triangle
Let A(1, 0)$A(1, 0)$, B(2, -1)$B(2, -1)$ and C((7)/(3), (4)/(3))$C\left(\frac{7}{3}, \frac{4}{3}\right)$ be three points. If the equation of the bisector of the angle ABC$ABC$ is α x + β y = 5$\alpha x + \beta y = 5$, then the value of α² + β²$\alpha^2 + \beta^2$ is
A.8$8$
B.5$5$
C.13$13$
D.10$10$
Solution
Related Formula
Angle bisector divides the opposite side in the ratio of adjacent sides: (BD)/(DC) = (AB)/(BC)$\frac{BD}{DC} = \frac{AB}{BC}$ (Internal Bisector Theorem).
Core Logic
Angle Bisector diagram for Q13
Calculate lengths AB$AB$ and BC$BC$ (wait, we need bisector of angle ABC$ABC$, so it intersects AC$AC$ at D$D$, so (AD)/(DC) = (AB)/(BC)$\frac{AD}{DC} = \frac{AB}{BC}$).
When asked for a specific angle bisector in a coordinate triangle, using the Angle Bisector Theorem (ratio trick) to find a second point is much faster than computing formulas of bisectors between lines.
Chapter Mix
Class 11 Maths: Straight Lines
More Straight Lines Questions — jee_main_2026_21_jan_morning
Practice past-year questions one chapter at a time. Pick an exam → subject → chapter and get every PYQ for that topic — pulled together from all past papers — with the chapter's key formulas alongside.