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Point P (a, b) is reflected in the x-axis to P’ (5, –2). Write down the values of a and b. P” is the image of P when reflected in the y-axis. Write down the co-ordinates of P”. - Mathematics

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Question

  1. Point P (a, b) is reflected in the x-axis to P’ (5, –2). Write down the values of a and b.
  2. P” is the image of P when reflected in the y-axis. Write down the co-ordinates of P”.
  3. Name a single transformation that maps P’ to P”.
Sum

Solution

  1. We know Mx (x, y) = (x, –y)
    P’ (5, –2) = reflection of P (a, b) in x-axis.
    Thus, the co-ordinates of P are (5, 2).
    Hence, a = 5 and b = 2.
  2. P” = image of P (5, 2) reflected in y-axis = (–5, 2)
  3. Single transformation that maps P’ to P” is the reflection in origin.
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Chapter 12: Reflection - Exercise 12 (B) [Page 170]

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Selina Mathematics [English] Class 10 ICSE
Chapter 12 Reflection
Exercise 12 (B) | Q 3 | Page 170

RELATED QUESTIONS

Attempt this question on graph paper.

  1. Plot A (3, 2) and B (5, 4) on graph paper. Take 2 cm = 1 unit on both the axes.
  2. Reflect A and B in the x-axis to A’ and B’ respectively. Plot these points also on the same graph paper.
  3. Write down:
    1. the geometrical name of the figure ABB’A’;
    2. the measure of angle ABB’;
    3. the image of A” of A, when A is reflected in the origin.
    4. the single transformation that maps A’ to A”.

Points (3, 0) and (–1, 0) are invariant points under reflection in the line L1; points (0, –3) and (0, 1) are invariant points on reflection in line L2.

  1. Name or write equations for the lines L1 and L2.
  2. Write down the images of the points P (3, 4) and Q (–5, –2) on reflection in line L1. Name the images as P’ and Q’ respectively.
  3. Write down the images of P and Q on reflection in L2. Name the images as P” and Q” respectively.
  4. State or describe a single transformation that maps P’ onto P''.

A point P (a, b) is reflected in the x-axis to P’ (2, –3). Write down the values of a and b. P” is the image of P, reflected in the y-axis. Write down the co-ordinates of P”. Find the co-ordinates of P”’, when P is reflected in the line, parallel to y-axis, such that x = 4.


The point P (5, 3) was reflected in the origin to get the image P’.

  1. Write down the co-ordinates of P’.
  2. If M is the foot of the perpendicular from P to the x-axis, find the co-ordinates of M.
  3. If N is the foot of the perpendicular from P’ to the x-axis, find the co-ordinates of N.
  4. Name the figure PMP’N.
  5. Find the area of the figure PMP’N.

The point P (3, 4) is reflected to P’ in the x-axis; and O’ is the image of O (the origin) when reflected in the line PP’. Write:

  1. the co-ordinates of P’ and O’.
  2. the length of the segments PP’ and OO’.
  3. the perimeter of the quadrilateral POP’O’.
  4. the geometrical name of the figure POP’O’.

A (1, 1), B (5, 1), C (4, 2) and D (2, 2) are vertices of a quadrilateral. Name the quadrilateral ABCD. A, B, C, and D are reflected in the origin on to A’, B’, C’ and D’ respectively. Locate A’, B’, C’ and D’ on the graph sheet and write their co-ordinates. Are D, A, A’ and D’ collinear?


  1. The point P (2, –4) is reflected about the line x = 0 to get the image Q. Find the co-ordinates of Q.
  2. The point Q is reflected about the line y = 0 to get the image R. Find the co-ordinates of R.
  3. Name the figure PQR.
  4. Find the area of figure PQR.

A’ and B’ are images of A (-3, 5) and B (-5, 3) respectively on reflection in y-axis. Find: (

a) the co-ordinates of A’ and B’.

(b) Assign special name of quadrilateral AA’B’B.

(c) Are AB’ and BA’ equal in length?


Using a graph paper, plot the point A (6, 4) and B (0, 4).

(a) Reflect A and B in the origin to get the image A’ and B’.

(b) Write the co-ordinates of A’ and B’.

(c) Sate the geometrical name for the figure ABA’B’.

(d) Find its perimeter.


Use a graph paper for this question.

(Take 2 cm = 1 unit on both x and y axes)

  1. Plot the following points: A(0, 4), B(2, 3), C(1, 1) and D(2, 0).
  2. Reflect points B, C, D on the y-axis and write down their coordinates. Name the images as B', C', D' respectively.
  3. Join the points A, B, C, D, D', C', B' and A in order, so as to form a closed figure. Write down the equation to the line about which if this closed figure obtained is folded, the two parts of the figure exactly coincide.

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