Hi, Could someone show me a proof that the two-dimensional del-squared operator is invariant under a rotation of axes in Cartesian co-ordinates? Thanks.
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Originally Posted by RET7 Hi, Could someone show me a proof that the two-dimensional del-squared operator is invariant under a rotation of axes in Cartesian co-ordinates? Thanks. Under a counter-clockwise rotation by angle : where x' and y' are the new Cartesian coordinates. Then: . Therefore: . In a similar way you get: . Now add the two expressions together and you have , since .
Last edited by mr fantastic; Feb 13th 2008 at 05:25 PM.
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