Use definition to check continuity:
. Let >0 be given.can we find >0 such that if
we know that
[img alt="-1\leq sinx\leq1" src="http://latex.codecogs.com/gif.latex?-1%5Cleq%20sinx%5Cleq1" >
then we can write
therefore it is continous at (0,0)
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