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Question
The point P(a, b) is first reflected in the origin and then reflected in the y-axis to P’. If P’ has co-ordinates (4, 6); evaluate a and b.
Solution
MO (a, b) = (–a, –b)
My (–a, –b) = (a, –b)
Thus, we get the co-ordinates of the point P’ as (a, –b). It is given that the co-ordinates of P’ are (4, 6).
On comparing the two points, we get, a = 4 and b = –6
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RELATED QUESTIONS
Complete the following table:
| Point | Transformation | Image | |
| (a) | (5, –7) | -------------------- | (–5, 7) |
| (b) | (4, 2) | Reflection in x-axis | ------- |
| (c) | ------- | Reflection in y-axis | (0, 6) |
| (d) | (6, –6) | -------------------- | (–6, 6) |
| (e) | (4, –8) | -------------------- | (–4, –8) |
State the co-ordinates of the following point under reflection in y-axis:
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x = 0
Point A (1,-5) is mapped as A' on reflection in the line y= l . The point B (-5, 1) is mapped as B' on reflection in the line y=4. Write the co-ordinates of A' and B'. Calculate AB'.
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The point P(3, 4) is reflected to P’ in the x-axis and O’ is the image of O (the Origin) in the line PP’ Find :
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(iii) The perimeter of the quadrilateral POP’O’
(iv) What is the special name of the quadrilateral POP’O’.
Using graph paper and taking 1 cm = 1 unit along both x-axis and y-axis.
(i) Plot the points A (- 4, 4) and B (2, 2).
(ii) Reflect A and B in the origin to get the images A’ and B’ respectively.
(iii) Write down the co-ordinates of A’ and B’.
(iv) Give the geometrical name for the figure ABA’B’.
(v) Draw and name its lines of symmetry.
