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Let A(a,0) and B(b,0) be fixed distinct ...

Let `A(a,0) and B(b,0)` be fixed distinct points on the x-axis, none of which coincides with the `O(0,0)`, and let C be a point on the y-axis. Let L be a line through the `O(0,0)` and perpendicular to the line AC. The locus of the point of intersection of the lines L and BC if C varies along is (provided `c^2 +ab != 0`)

A

(a) `(x^(2))/(a)+(y^(2))/(b) =x`

B

(b) `(x^(2))/(a)+(y^(2))/(b) =y`

C

(c) `(x^(2))/(b)+(y^(2))/(a)=x`

D

(d) `(x^(2))/(b)+(y^(2))/(a) =y`

Text Solution

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To solve the problem step by step, we will derive the locus of the point of intersection of the lines L and BC as point C varies along the y-axis. ### Step 1: Define the points and their coordinates Let: - Point A be \( A(a, 0) \) - Point B be \( B(b, 0) \) - Point C be \( C(0, k) \) where \( k \) varies along the y-axis. - The origin \( O(0, 0) \) ### Step 2: Find the equation of line AC The slope of line AC can be calculated as follows: \[ \text{slope of AC} = \frac{k - 0}{0 - a} = -\frac{k}{a} \] Using the point-slope form, the equation of line AC can be written as: \[ y - 0 = -\frac{k}{a}(x - a) \] Rearranging gives: \[ y = -\frac{k}{a}x + k \] ### Step 3: Find the slope of line L Line L is perpendicular to line AC. The slope of line L is the negative reciprocal of the slope of line AC: \[ \text{slope of L} = \frac{a}{k} \] Since line L passes through the origin, its equation is: \[ y = \frac{a}{k}x \] ### Step 4: Find the equation of line BC The slope of line BC can be calculated as follows: \[ \text{slope of BC} = \frac{k - 0}{0 - b} = -\frac{k}{b} \] Using the point-slope form, the equation of line BC can be written as: \[ y - 0 = -\frac{k}{b}(x - b) \] Rearranging gives: \[ y = -\frac{k}{b}x + k \] ### Step 5: Find the point of intersection of lines L and BC To find the intersection point (let's call it point N), we need to solve the equations of lines L and BC: 1. \( y = \frac{a}{k}x \) (Equation of line L) 2. \( y = -\frac{k}{b}x + k \) (Equation of line BC) Setting these two equations equal to each other: \[ \frac{a}{k}x = -\frac{k}{b}x + k \] ### Step 6: Solve for x Rearranging gives: \[ \frac{a}{k}x + \frac{k}{b}x = k \] Factoring out \( x \): \[ x\left(\frac{a}{k} + \frac{k}{b}\right) = k \] Thus, \[ x = \frac{k}{\frac{a}{k} + \frac{k}{b}} = \frac{kb}{a + \frac{k^2}{b}} = \frac{kb^2}{ab + k^2} \] ### Step 7: Substitute x back to find y Substituting \( x \) back into the equation of line L: \[ y = \frac{a}{k}\left(\frac{kb^2}{ab + k^2}\right) = \frac{ab^2}{ab + k^2} \] ### Step 8: Find the locus The coordinates of point N are: \[ N\left(\frac{kb^2}{ab + k^2}, \frac{ab^2}{ab + k^2}\right) \] Let \( x = \frac{kb^2}{ab + k^2} \) and \( y = \frac{ab^2}{ab + k^2} \). Cross-multiplying gives: \[ x(ab + k^2) = kb^2 \] \[ abx + k^2x = kb^2 \] Rearranging gives: \[ k^2x = kb^2 - abx \] Dividing by \( k \) (assuming \( k \neq 0 \)): \[ kx = b^2 - ab\frac{x}{k} \] This leads to: \[ \frac{x^2}{b} + \frac{y^2}{a} = x \] ### Conclusion The locus of the point of intersection of lines L and BC as point C varies along the y-axis is given by: \[ \frac{x^2}{b} + \frac{y^2}{a} = x \]

To solve the problem step by step, we will derive the locus of the point of intersection of the lines L and BC as point C varies along the y-axis. ### Step 1: Define the points and their coordinates Let: - Point A be \( A(a, 0) \) - Point B be \( B(b, 0) \) - Point C be \( C(0, k) \) where \( k \) varies along the y-axis. - The origin \( O(0, 0) \) ...
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