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The point (4, 1) undergoes the following two successive transformations: (i) Reflection about the line y = x(ii) Translation through a distance 2 units along the positive x-axis Then the fina - Mathematics

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Question

The point (4, 1) undergoes the following two successive transformations: 
(i) Reflection about the line y = x
(ii) Translation through a distance 2 units along the positive x-axis Then the final coordinates of the point are ______.

Options

  • (4, 3)

  • (3, 4)

  • (1, 4)

  • `7/2, 7/2`

MCQ
Fill in the Blanks

Solution

The point (4, 1) undergoes the following two successive transformations: 
(i) Reflection about the line y = x
(ii) Translation through a distance 2 units along the positive x-axis Then the final coordinates of the point are (3, 4).

Explanation:

Let the reflection of A(4, 1) in y = x be B(a, b) mid-point of AB

= `((4 + a)/2, (1 + b)/2)` which lies on y = x

⇒ `(4 + "a")/2 = (1 + b)/2`

⇒ 4 + a = 1 + b

⇒ a – b = – 3  .......(i)

The slope of the line y = x is 1 and slope of AB = `(b - 1)/(a - 4)`

∴ `1((b - 1)/(a - 4)) = - 1`

⇒ b – 1 = – a + 4

⇒ a + b = 5   ....(ii)

Solving equation (i) and equation (ii) we get

a = 1 and b = 4

∴  The point after translation is (1 + 2, 4) or (3, 4).

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Chapter 10: Straight Lines - Exercise [Page 182]

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NCERT Exemplar Mathematics [English] Class 11
Chapter 10 Straight Lines
Exercise | Q 37 | Page 182

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