Centre of Rotation

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The transformation that rotates each point in the shape at a certain number of degrees around that point is called rotation. 
• The shape rotates counterclockwise when the number of degrees is positive 
• rotates clockwise when the number of degrees is negative. The general rule of transformation of rotation about the origin is as follows. 
• To rotate 90º: (x,y) → (-y, x) 
• To rotate 180º (x,y) → (-x,-y) 
• To rotate 270º (x,y) → (y, -x) 
Some important point related to Rotation Calculation:
• Center of Rotation 
• Axis of Rotation The center of rotation is a point about which a plane figure rotates. This point does not move during the rotation.

HOW DO YOU FIND THE CENTRE OF ROTATION?
Draw a line between the corresponding points
Construct the perpendicular bisect of these points
Do this for each point until they cross
That is your center of rotation

On a piece of graph paper, draw the shapes given on the side. And follow the instructions given below. 

Notes for your Reference