Mathematics
The point P(4, -7) is reflected in the origin to point P'. The point P' is then reflected in x-axis to the point P".
(i) Find the co-ordinates of P'.
(ii) Find the co-ordinates of P".
(iii) Write down a single transformation that maps P onto P".
Reflection
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Answer
(i) We know that,
Rule to find reflection of a point in origin :
Change the sign of abscissa and ordinate.
∴ Point P'(-4, 7) is the image of point P(4, -7) on reflection in origin.
Hence, P' = (-4, 7).
(ii) We know that,
Rule to find reflection of a point in x-axis :
Change the sign of ordinate i.e. y-coordinate.
Retain the abscissa i.e. x-coordinate.
∴ Point P"(-4, -7) is the image of point P'(-4, 7) on reflection in x-axis.
Hence, P" = (-4, -7).
(iii) P(4, -7) ⇒ P"(-4, -7)
A transformation that keeps the y-coordinate the same and changes the sign of the x-coordinate is a reflection in the y-axis.
Hence, single transformation that maps P into P" is reflection in the y-axis.
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