document.write( "Question 896411: • Let x = r(cos u + i sin u)
\n" ); document.write( "• Let y = t(cos v + i sin v)
\n" ); document.write( "Prove that xy = rt(cos(u+v) + i sin(u+v)) and prove that \r
\n" ); document.write( "\n" ); document.write( "The radius (or modulus) of the product xy is rt \r
\n" ); document.write( "\n" ); document.write( "I have to solve and justify the steps. I know that I will plug in the cos u.... and cos v... I have read the chapter and stared at the work for awhile but I am not getting anywhere! \n" ); document.write( "

Algebra.Com's Answer #543491 by Edwin McCravy(20055) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "Multiply equals by equals:\r\n" );
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document.write( "Use FOIL\r\n" );
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document.write( "since \r\n" );
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document.write( "factor i out of the middle two terms\r\n" );
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document.write( "Move the last term next to the first term:\r\n" );
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document.write( "Use double angle formulas \r\n" );
document.write( "and \r\n" );
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document.write( "You might swap the terms of the imaginary part:\r\n" );
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document.write( "and you have:\r\n" );
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document.write( "Edwin

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