# prove isomorphism in distributive category

I have a question, I want to prove cartesian closed category with finite coproduct is distributive category. but do not know how to prove $A*(B+C) \sim A*B+A*C$ is isomorphism from the property of exponential object, can anyone help me? Thank you.

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What's the problem with Harry's answer on math.MO? mathoverflow.net/questions/52804 –  t.b. Jan 23 '11 at 1:39