Let A(1, 2) and C(-3, -6) be two diagonally opposite vertices of a rhombus, whose sides AD and BC are parallel to the line 7x - y = 14. If B(alpha, beta) and D(gamma, delta) are the other two vertices, then |alpha + beta + gamma + delta| is equal to :

Solution & Explanation

### Related Formula In a rhombus, diagonals bisect each other. Therefore, the midpoint of diagonal AC is the same as the midpoint of diagonal BD. ### Core Logic
Properties of Rhombus diagram for Q4 - JEE Main 2026 Evening
Properties of Rhombus diagram for Q4 - JEE Main 2026 Evening
Given the coordinates of vertices A(1, 2) and C(-3, -6), we can find the midpoint O of the diagonal AC. x_m = frac1 + (-3)2 = -1 y_m = frac2 + (-6)2 = -2 So, the midpoint is (-1, -2). Let the coordinates of B and D be (alpha, beta) and (gamma, delta) respectively. Since the midpoint of BD is also (-1, -2): fracalpha+gamma2 = -1 implies alpha+gamma = -2 fracbeta+delta2 = -2 implies beta+delta = -4 ### Step 1: Final Calculation We need the absolute value of the sum of the coordinates of B and D: |alpha + beta + gamma + delta| = |(alpha + gamma) + (beta + delta)| = |-2 - 4| = |-6| = 6 ### Pattern Recognition The extra information regarding the parallel line 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. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Straight Lines

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Q4 jee_main_2026_21_jan_morning Equilateral Triangle Between Parallel Lines
Let a point A lie between the parallel lines L_1 and L_2 such that its distances from L_1 and 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 L_1 and L_2 respectively, is:
  • A. 15sqrt6
  • B. 27
  • C. 21sqrt3
  • D. 12sqrt2

Solution

### Related Formula textArea of Equilateral Triangle = fracsqrt34 a^2 Where a is the side length. ### Core Logic Let the side of the equilateral triangle be a. Let theta be the angle between the side AC and the parallel line L_2. Then, the angle between the side AB and the parallel line L_1 can be expressed via alternate geometry. Given distances from 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
Equilateral triangle between parallel lines diagram for Q4 - JEE Main 2026 Morning
From vertex C to line passing through A parallel to L_1, L_2, the perpendicular distance is 3. In the right triangle formed, we have: sin theta = frac3a Similarly, point B lies on L_1. The perpendicular distance from A to L_1 is 6. However, combining the overall heights between the parallel lines, the total distance between L_1 and L_2 is 6 + 3 = 9. The projection of side BC (which connects L_1 and L_2) vertically is 9. sin(60^circ + theta) = frac9a ### Step 2: Solve the trigonometric system Expand sin(60^circ + theta): fracsqrt32 cos theta + frac12 sin theta = frac9a Substitute sin theta = frac3a and cos theta = sqrt1 - sin^2 theta = sqrt1 - frac9a^2: fracsqrt32 sqrt1 - frac9a^2 + frac12 left(frac3aright) = frac9a sqrt3 sqrt1 - frac9a^2 + frac3a = frac18a sqrt3 sqrt1 - frac9a^2 = frac15a Squaring both sides: 3 left(1 - frac9a^2right) = frac225a^2 3 - frac27a^2 = frac225a^2 3 = frac252a^2 Rightarrow a^2 = 84 ### Step 3: Calculate Area textArea of Delta ABC = fracsqrt34 a^2 = fracsqrt34 times 84 = 21sqrt3 ### Pattern Recognition When a rigid polygon (like an equilateral triangle or square) is wedged between parallel lines, set a base orientation angle theta for one edge and use rotational shifts (e.g., 60^circ + theta) to project heights. Expanding the sine addition formula instantly yields the side length. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Straight Lines Class 11 Maths: Trigonometric Functions
Q7 jee_main_2026_22_january_evening Orthocenter and Concurrency
Among the statements: (S1): If A(5,-1) and B(-2,3) are two vertices of a triangle, whose orthocentre is (0,0), then its third vertex is (-4,-7) and (S2): If positive numbers 2a, b, c are three consecutive terms of an A.P., then the lines ax + by + c = 0 are concurrent at (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 is perpendicular to BC, Altitude from B is perpendicular to AC. Concurrency of lines: ax+by+c=0 passes through (x_0, y_0) if ax_0+by_0+c=0 holds. ### Core Logic
Triangle orthocenter diagram for Q7 - JEE Main 2026 Evening
Triangle orthocenter diagram for Q7 - JEE Main 2026 Evening
Statement 1: Let third vertex be C(h,k) and orthocenter O(0,0). - Slope AO cdot Slope BC = -1 implies left(frac-15right) cdot left(frack-3h+2right) = -1 implies 5h - k + 13 = 0 - Slope BO cdot Slope AC = -1 implies left(frac3-2right) cdot left(frack+1h-5right) = -1 implies 4k = 7h Solving simultaneously gives h = -4, k = -7 implies C(-4,-7). Statement 1 is correct. Statement 2: 2a, b, c in A.P. implies 2b = 2a + c implies 2a - 2b + c = 0. Comparing with ax + by + c = 0 gives 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. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Straight Lines
Q4 jee_main_2026_23_january_morning Area and Distance
A rectangle is formed by the lines x = 0, y = 0, x = 3 and y = 4. Let the line L be perpendicular to 3x + y + 6 = 0 and divide the area of the rectangle into two equal parts. Then the distance of the point left(frac12, -5right) from the line L is equal to:
  • A. 2sqrt5
  • B. 3sqrt10
  • C. sqrt10
  • D. 2sqrt10

Solution

### Related Formula textDistance = frac|Ax_1 + By_1 + C|sqrtA^2 + B^2 ### Core Logic 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
Area and Distance diagram for Q4 - JEE Main 2026 Morning
The vertices of the rectangle are (0,0), (3,0), (3,4), and (0,4). Its center is at left(frac32, 2right). ### Step 1: Equation of Line L The line L is perpendicular to 3x + y + 6 = 0. The slope of this reference line is -3. Thus, the slope of L is m = frac13. The equation of L passing through left(frac32, 2right) is: y - 2 = frac13left(x - frac32right) y = fracx3 - frac12 + 2 Rightarrow y = fracx3 + frac32 Multiplying by 6 gives: 6y = 2x + 9 Rightarrow 2x - 6y + 9 = 0 ### Step 2: Calculate Distance We need the perpendicular distance from left(frac12, -5right) to the line 2x - 6y + 9 = 0: D = fracleft| 2left(frac12right) - 6(-5) + 9 right|sqrt2^2 + (-6)^2 D = frac|1 + 30 + 9|sqrt4 + 36 = frac40sqrt40 = sqrt40 = 2sqrt10 ### Pattern Recognition Area bisectors for symmetric geometric figures (rectangles, circles, ellipses) always pass exactly through their geometric center. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Straight Lines
Q13 jee_main_2026_24_january_morning Angle Bisectors of a Triangle
Let A(1, 0), B(2, -1) and Cleft(frac73, frac43right) be three points. If the equation of the bisector of the angle ABC is alpha x + beta y = 5, then the value of alpha^2 + beta^2 is
  • A. 8
  • B. 5
  • C. 13
  • D. 10

Solution

### Related Formula Angle bisector divides the opposite side in the ratio of adjacent sides: fracBDDC = fracABBC (Internal Bisector Theorem). ### Core Logic
Angle Bisector diagram for Q13
Angle Bisector diagram for Q13
Calculate lengths AB and BC (wait, we need bisector of angle ABC, so it intersects AC at D, so fracADDC = fracABBC). ### Step 1: Side Lengths AB = sqrt(2-1)^2 + (-1-0)^2 = sqrt1 + 1 = sqrt2 BC = sqrtleft(frac73-2right)^2 + left(frac43-(-1)right)^2 = sqrtfrac19 + frac499 = sqrtfrac509 = frac5sqrt23 Ratio fracABBC = fracsqrt2frac5sqrt23 = frac35. ### Step 2: Coordinates of D Point D divides AC internally in ratio 3:5. x = frac3(7/3) + 5(1)3+5 = frac7+58 = frac128 = frac32 y = frac3(4/3) + 5(0)3+5 = frac48 = frac12 D = left(frac32, frac12right) ### Step 3: Equation of Bisector The bisector passes through B(2,-1) and D(3/2, 1/2). Slope m = frac1/2 - (-1)3/2 - 2 = frac3/2-1/2 = -3 Equation: y - (-1) = -3(x - 2) y + 1 = -3x + 6 Rightarrow 3x + y = 5
Angle Bisector diagram for Q13
Angle Bisector diagram for Q13
### Step 4: Final Value Calculation Comparing 3x + y = 5 with alpha x + beta y = 5, we get alpha = 3, beta = 1. alpha^2 + beta^2 = 9 + 1 = 10 ### Pattern Recognition 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. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Straight Lines

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