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Statement I Reflection of the point (5,1...

Statement I Reflection of the point (5,1) in the line `x+y=0` is `(-1,-5)`
Statement II Reflection of a point `P(alpha,beta)` in the line `ax+by+c= 0 ` is ` Q (alpha',beta' ) " if " ((alpha +alpha')/2 ,(beta +beta' )/2)` lies on the line .

A

Statement I is true ,statement II is true , statement II is a correct explanation for statement I

B

Statement I is true ,statement II is true statement II is not a correct explanation for statement I

C

Statement I is true ,statement II is false

D

Statement I is false ,statement II is true

Text Solution

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The correct Answer is:
To solve the problem, we need to verify both statements regarding the reflection of a point in a line. ### Step 1: Find the reflection of the point (5, 1) in the line x + y = 0. 1. **Identify the given point and line**: - Point A = (5, 1) - Line equation: x + y = 0 2. **Find the slope of the line**: - The line x + y = 0 can be rewritten as y = -x. The slope (m) of this line is -1. 3. **Find the slope of the perpendicular line**: - The slope of the line perpendicular to x + y = 0 is the negative reciprocal of -1, which is 1. 4. **Equation of the perpendicular line through point A (5, 1)**: - Using the point-slope form: \[ y - 1 = 1(x - 5) \implies y = x - 4 \] 5. **Find the intersection point (M) of the two lines**: - Set the equations equal to each other: \[ x - 4 = -x \implies 2x = 4 \implies x = 2 \] - Substitute x = 2 into y = -x: \[ y = -2 \] - Thus, the intersection point M is (2, -2). 6. **Find the reflection point B (x1, y1)**: - Since M is the midpoint of A and B, we have: \[ M = \left(\frac{x_1 + 5}{2}, \frac{y_1 + 1}{2}\right) = (2, -2) \] - This gives us two equations: \[ \frac{x_1 + 5}{2} = 2 \implies x_1 + 5 = 4 \implies x_1 = -1 \] \[ \frac{y_1 + 1}{2} = -2 \implies y_1 + 1 = -4 \implies y_1 = -5 \] - Therefore, the reflection point B is (-1, -5). ### Step 2: Verify Statement I - Statement I claims that the reflection of the point (5, 1) in the line x + y = 0 is (-1, -5). - From our calculations, we found that the reflection point is indeed (-1, -5). Thus, Statement I is **correct**. ### Step 3: Verify Statement II - Statement II states that the reflection of a point P(α, β) in the line ax + by + c = 0 is Q(α', β') if the midpoint ((α + α')/2, (β + β')/2) lies on the line. 1. **Using our earlier findings**: - We found the midpoint M = (2, -2) for points A(5, 1) and B(-1, -5). - We need to check if M lies on the line x + y = 0: \[ 2 + (-2) = 0 \] - Since this is true, it confirms that the midpoint lies on the line. 2. **Conclusion for Statement II**: - Since we verified that the midpoint lies on the line, Statement II is also **correct**. ### Final Conclusion Both Statement I and Statement II are correct. ---
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