Describe fully, and carry out reflections in lines and rotations about any point
Reflection
Reflection means we take the mirror image of a shape, where the mirror would be, we call it the line of symmetry. it stays the same but changes in direction. You may find questions that will ask you for the reflection of a line.
You can use tracing paper to help reflect your shape.
Rotation
Every point on a rotated shape is at the same distance from the point of rotation. It stays the same size, but changes in direction.
Rotation about a point
Imagine a shape that has been cut out from some paper, and placed on the graph. If you want to rotate it about a spot, you can stick a pin where the 'spot' is, and as you spin the shape, that is rotation about a spot.
Cutting out the shape is a useful way to practice rotation, but you will not have scissors in your exam!
Remember, every point on the rotated shape must be the same distance from the spot as the original shape.
Rotation about a centre of rotation.
Imagine the shape being turned round a point, like you are drawing a circle.
To rotate an object, again take each corner one by one and rotate it using a protractor. If the rotation is by 90o,180o,270^{o}then we you can use the grid on the paper.
For example, if you want to rotate the point (2,3), about the origin, 90^{o} clockwise, insteading of going right 2 steps and up 3 steps, we go down 2 steps and right 3 steps, giving you the coordinates (3,2)
(remember up and down give you ycoordinate, and left and right give you x coordinates, it doesn't matter what order it is in!)
There are no tricks to finding the centre of rotation, it is done by observing, but remember every point must be at the same distance.
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