document.write( "Question 1153915: Find the exact values of sin(2u),cos(2u),tan(2u)using the half-angle formulas.
\n" ); document.write( "sin u = -3/5, 0 \n" ); document.write( "
Algebra.Com's Answer #776240 by ikleyn(52790)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "(1)  First, you should not use half-angle formulas.\r\n" );
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document.write( "(2)  Second, for the given purposes, special formulas do exist in Trigonometry, that are called the double argument formulas.\r\n" );
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document.write( "     These formulas are\r\n" );
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document.write( "         \"cos%282alpha%29+=+2%2Acos%5E2%28alpha%29+-+1\"\r\n" );
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document.write( "         \"sin%282alpha%29+=+2%2Asin%28alpha%29%2Acos%28alpha%29\"\r\n" );
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document.write( "         \"tan%282alpha%29\" = \"%282%2Atan%28alpha%29%29%2F%281-tan%5E2%28alpha%29%29\".\r\n" );
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document.write( "(3)  So, start calculating\r\n" );
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document.write( "         \"cos%28alpha%29\" = +/- \"sqrt%281-sin%5E2%28alpha%29%29\" = +/- \"sqrt%281-%28-3%2F5%29%5E2%29\" = +/- \"sqrt%281-9%2F25%29\" = +/- \"sqrt%2816%2F25%29\" = +/- \"4%2F5\".\r\n" );
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document.write( "      Which sign to chose there, is the unknown fact - the problem does not provide a necessary info for it.\r\n" );
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document.write( "      In this sense, your input is FATALLY incomplete.\r\n" );
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document.write( "(4)  Having values of  \"sin%28alpha%29\"  and \"cos%28alpha%29\", you should substitute them into formulas for double arguments above,\r\n" );
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document.write( "     and complete the assignment in this way.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Again, the input is FATALLY INCOMPLETE; therefore, I can not continue.\r
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\n" ); document.write( "\n" ); document.write( "The fact that the input is incomplete, is your FAULT.\r
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\n" ); document.write( "\n" ); document.write( "and my conclusion is that the problem is presented in the post EXTREMELY UNPROFESSIONALLY.\r
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