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| 1. | P and Q have co-ordinates (0, 5) and (-2, 4). (a) P is invariant when reflected in an axis. Name the axis. (b) Find the image of Q on reflection in the axis found in (i). (c) (0, k) on reflection in the origin is invariant. Write the value of k. (d) Write the co-ordinates of the image of Q, obtained by reflecting it in the origin followed by reflection in x-axis. | 
| Answer» (a) Any point that remains unaltered under a given transformation is called an invariant. It is given that P (0, 5) is invariant when reflected in an axis. Clearly, when P is reflected in the y-axis then it will remain invariant. Thus, the required axis is the y-axis. (b) The co-ordinates of the image of Q (-2, 4) when reflected in y-axis is (2, 4). (c) (0, k) on reflection in the origin is invariant. We know the reflection of origin in origin is invariant. Thus, k = 0. (d) Co-ordinates of image of Q (-2, 4) when reflected in origin = (2, -4) Co-ordinates of image of (2, -4) when reflected in x-axis = (2, 4) Thus, the co-ordinates of the point are (2, 4). | |