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A line passing through the point A(9,0) makes an angle of 30^circ with the positive direction of x-axis. If this line is rotated about A through an angle of 15^circ in the clockwise direction, then its equation in the new position is

Solution & Explanation

### Related Formula y - y_1 = tan(theta)(x - x_1) ### Core Logic
Rotation of Axes and Lines diagram for Q1 - JEE Main 2024 Morning
Rotation of Axes and Lines diagram for Q1 - JEE Main 2024 Morning
The initial line makes an angle of 30^circ with the positive x-axis. It is rotated clockwise by 15^circ about the point A(9, 0). The new angle made by the line with the positive direction of the x-axis is 30^circ - 15^circ = 15^circ. ### Step 1: Equation of the new line The equation of the line passing through A(9, 0) with a slope of tan 15^circ is: textEq^n: y - 0 = tan 15^circ (x - 9) We know that tan 15^circ = 2 - sqrt3. y = (2 - sqrt3) (x - 9) ### Step 2: Rearranging to match options Dividing by (2 - sqrt3): fracy2 - sqrt3 = x - 9 Notice that 2 - sqrt3 = -(sqrt3 - 2). Thus: frac-ysqrt3 - 2 = x - 9 fracysqrt3 - 2 + x = 9 ### Pattern Recognition A clockwise rotation decreases the angle of inclination. Calculate the new angle, find its tangent, and carefully algebraicize the denominator to match the given option forms. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Straight Lines

Reference Study Guides

More Straight Lines Previous-Year Questions — Page 5

Q23 jee_main_2024_31_jan_evening Parallelogram Properties
Let A(-2, -1), B(1, 0), C(alpha, beta) and D(gamma, delta) be the vertices of a parallelogram ABCD. If the point C lies on 2x - y = 5 and the point D lies on 3x - 2y = 6, then the value of |alpha + beta + gamma + delta| is equal to
Numerical Answer. Answer: 32 to 32

Solution

### Related Formula textIn a parallelogram, midpoints of diagonals coincide: left(fracx_A+x_C2, fracy_A+y_C2right) = left(fracx_B+x_D2, fracy_B+y_D2right) ### Core Logic
Parallelogram Properties diagram for Q23 - JEE Main 2024 Evening
Parallelogram Properties diagram for Q23 - JEE Main 2024 Evening
Given diagonals AC and BD bisect each other: alpha - 2 = gamma + 1 implies alpha - gamma = 3 quad dots (1) beta - 1 = delta + 0 implies beta - delta = 1 quad dots (2) Point C(alpha, beta) lies on 2x - y = 5 implies 2alpha - beta = 5 quad dots (3) Point D(gamma, delta) lies on 3x - 2y = 6 implies 3gamma - 2delta = 6 quad dots (4) From (1) and (2), substitute gamma = alpha - 3 and delta = beta - 1 into (4): 3(alpha - 3) - 2(beta - 1) = 6 3alpha - 9 - 2beta + 2 = 6 implies 3alpha - 2beta = 13 quad dots (5) Solve (3) and (5): From (3), beta = 2alpha - 5. Substitute in (5): 3alpha - 2(2alpha - 5) = 13 -alpha + 10 = 13 implies alpha = -3 So, beta = 2(-3) - 5 = -11. From earlier substitutions: gamma = -3 - 3 = -6 delta = -11 - 1 = -12 Sum of variables: |alpha + beta + gamma + delta| = |-3 - 11 - 6 - 12| = |-32| = 32 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Straight Lines
Q10 jee_main_2024_31_jan_morning Properties of Parallelogram
Let alpha, beta, gamma, delta in Z and let A (alpha, beta), B (1, 0), C (gamma, delta) and D (1, 2) be the vertices of a parallelogram ABCD. If AB = sqrt10 and the points A and C lie on the line 3y = 2x + 1, then 2(alpha + beta + gamma + delta) is equal to
  • A. 10
  • B. 5
  • C. 12
  • D. 8

Solution

### Core Logic Let E be the midpoint of the diagonals AC and BD. Since ABCD is a parallelogram, the diagonals bisect each other.
Properties of Parallelogram diagram for Q10 - JEE Main 2024 Morning
Properties of Parallelogram diagram for Q10 - JEE Main 2024 Morning
Midpoint E from BD: left( frac1+12, frac0+22 right) = (1, 1). ### Step 1: Apply Midpoint on AC Midpoint E from AC: left( fracalpha+gamma2, fracbeta+delta2 right). Equating both: fracalpha+gamma2 = 1 implies alpha + gamma = 2 fracbeta+delta2 = 1 implies beta + delta = 2 ### Step 2: Final Value The expression requires 2(alpha + beta + gamma + delta). 2(2 + 2) = 2(4) = 8 *(Note: Additional conditions like AB = sqrt10 and the line equation are extraneous data not needed to find the sum).* ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Straight Lines

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