document.write( "Question 1043673: Please help me solve (12i)^1/2 to a+bi form
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Algebra.Com's Answer #658825 by ikleyn(52781)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "The general procedure on how to find the roots of a complex number is explained in the lesson\r
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\n" ); document.write( "\n" ); document.write( "If you just are familiar with complex numbers, operations on them, complex plane, trigonometric form of complex numbers -
\n" ); document.write( "    - then you will be able to understand it.\r
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\n" ); document.write( "\n" ); document.write( "If you are not familiar with this material, then you can learn on complex numbers from these lessons\r
\n" ); document.write( "\n" ); document.write( "    - Complex numbers and arithmetic operations on them\r
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\n" ); document.write( "\n" ); document.write( "    - Addition and subtraction of complex numbers in complex plane\r
\n" ); document.write( "\n" ); document.write( "    - Multiplication and division of complex numbers in complex plane\r
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document.write( "After this introduction, let me briefly explain you how to solve your problem.\r\n" );
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document.write( "So, you need to find \"sqrt%2812%2Ai%29\".\r\n" );
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document.write( "Write 12*i in the trigonometric form z = \"r%2A%28cos%28alpha%29+%2B+i%2Asin%28alpha%29%29\",\r\n" );
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document.write( "where \"r\" is the modulus and \"alpha\" is the argument (polar angle).\r\n" );
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document.write( "In your case,  z = 12*i  in trigonometric form is z = \"12%2A%28cos%28pi%2F2%29+%2B+i%2Asin%28pi%2F2%29%29\", so the modulus is r = 12 and the polar angle is \"alpha\" = \"pi%2F2\".\r\n" );
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document.write( "Now, to find the square root of this complex number, you have\r\n" );
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document.write( "  1.  to take a square root of the modulus: \"sqrt%28r%29\" = \"sqrt%2812%29\" = \"2%2Asqrt%283%29\".\r\n" );
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document.write( "  2.  to divide the argument (polar angle) by 2:  \"alpha%2F2\" = \"%28%28pi%2F2%29%29%2F2\" = \"pi%2F4\".\r\n" );
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document.write( "  3.  to consider the complex number \"z%5B1%5D\" = \"sqrt%28r%29%2A%28cos%28alpha%2F2%29+%2B+i%2Asin%28alpha%2F2%29%29\", which is in your case \r\n" );
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document.write( "      \"z%5B1%5D\" = \"sqrt%2812%29%2A%28cos%28pi%2F4%29+%2B+i%2Asin%28pi%2F4%29%29\" = \"2%2Asqrt%283%29%2A%28sqrt%282%29%2F2+%2B+i%2Asqrt%282%29%2F2%29\" = \"sqrt%283%29%2A%28sqrt%282%29+%2B+i%2Asqrt%282%29%29\" = \"sqrt%286%29%2A%281+%2B+i%29%29\" = \"sqrt%286%29+%2B+i%2Asqrt%286%29%29\".\r\n" );
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document.write( "      It is one of the two complex roots.  // Notice that the modulus of \"z%5B1%5D\" is \"sqrt%28r%29\" and the argument is \"alpha%2F2\" = \"pi%2F4\".\r\n" );
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document.write( "                                          // Also notice that the final expression for \"z%5B1%5D\" is just a + bi form.\r\n" );
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document.write( "  4.  to get the second root \"z%5B2%5D\" in trigonometric form, you have to use the same modulus as \"z%5B1%5D\" has, namely \"sqrt%28r%29\",  but use another \r\n" );
document.write( "      argument, which this time is \"alpha%2F2+%2B+2pi%2F2\" = \"alpha%2F2+%2B+pi\".\r\n" );
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document.write( "      Then your \"z%5B2%5D\" = \"sqrt%28r%29%2A%28cos%28alpha%2F2+%2B+pi%29+%2B+i%2Asin%28alpha%2F2+%2B+pi%29%29\" = \"sqrt%2812%29%2A%28cos%28pi%2F4+%2B+pi%29+%2B+i%2Asin%28pi%2F4+%2B+pi%29%29\" = \"2%2Asqrt%283%29%2A%28cos%285pi%2F4%29+%2B+i%2Asin%285pi%2F4%29%29\" = \r\n" );
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document.write( "                     = \"2%2Asqrt%283%29%2A%28%28-sqrt%282%29%2F2%29+%2B+i%2A%28-sqrt%282%29%2F2%29%29\" = \"sqrt%283%29%2A%28-sqrt%282%29+-+i%2Asqrt%282%29%29\" = \"-sqrt%283%29%2A%28sqrt%282%29+%2B+i%2Asqrt%282%29%29\" = \"-sqrt%286%29%2A%281+%2B+i%29\" = \"-sqrt%286%29+-+i%2Asqrt%286%29\".\r\n" );
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document.write( "      // Notice that \"z%5B2%5D\" = \"-z%5B1%5D\".\r\n" );
document.write( "      // All this long way with \"z%5B2%5D\" lead us to the opposite number to \"z%5B1%5D\".\r\n" );
document.write( "      // But now you know all the procedure, how it works for square roots of complex numbers.\r\n" );
document.write( "      // Surely, it may seem too complex, at the first glance.\r\n" );
document.write( "      // But there is a powerful symmetry in it, which work nicely for all n > 2.\r\n" );
document.write( "      // If you read the lessons I recommended you, you will be able to learn its real power and beauty.\r\n" );
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document.write( "Answer.  \"sqrt%2812%2Ai%29\" has two values: \"z%5B1%5D\" = \"sqrt%286%29+%2B+i%2Asqrt%286%29%29\" and \"z%5B2%5D\" = \"-z%5B1%5D\" = \"-sqrt%286%29+-+i%2Asqrt%286%29%29\".\r\n" );
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