Let f:[0,π)→[−1,1] be the function defined by f(x)=sin(2x). What is the subset S f
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of relation f (i.e. graph of f )? Define a congruence modulo 5 relation ≡ 5
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between integers in Z:a∈Z is said to be congruent modulo 5 to b∈Z, if a−b is divisible by 5 , and written as a≡ 5
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b. Prove: ≡ 5
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is an equivalence relation.