document.write( "Question 1058119: How do I solve the equation the equation sin(theta) - cos(theta) = sqrt( 2 ) ? \n" ); document.write( "
Algebra.Com's Answer #673155 by ikleyn(52852)\"\" \"About 
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\n" ); document.write( "How do I solve the equation the equation sin(theta) - cos(theta) = sqrt( 2 ) ?
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document.write( "\"sin%28theta%29+-+cos%28theta%29\" = \"sqrt%282%29\".\r\n" );
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document.write( "Multiply both sides by \"sqrt%282%29%2F2\". You will get\r\n" );
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document.write( "\"%28sqrt%282%29%2F2%29%2Asin%28theta%29+-+%28sqrt%282%29%2F2%29%2Acos%28theta%29\" = 1.             (1)\r\n" );
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document.write( "Notice and use that \"sqrt%282%29%2F2\" = \"cos%28pi%2F4%29\" = \"sin%28pi%2F4%29\".\r\n" );
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document.write( "Then from (*) you will get \r\n" );
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document.write( "\"cos%28pi%2F4%29%2Asin%28theta%29+-+sin%28pi%2F4%29%2Acos%28theta%29\" = 1.       (2)\r\n" );
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document.write( "Now use the formula sin(a)*cos(b) - cos(a)*sin(b) = sin(a-b). Then from (2) you will get\r\n" );
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document.write( "\"-sin%28pi%2F4-theta%29\" = 1.\r\n" );
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document.write( "It implies \r\n" );
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document.write( "\"pi%2F4+-+theta\" = \"3pi%2F2\".\r\n" );
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document.write( "Then \"theta\" = \"pi%2F4+-+3pi%2F2\" = \"-5pi%2F4\".\r\n" );
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document.write( "It is the same as \"theta\" = \"3pi%2F4\" in the interval 0 <= \"theta\" < \"2pi\".\r\n" );
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\n" ); document.write( "\n" ); document.write( "The plot below confirms the solution ( \"3pi%2F4\" ~= 2.33 )\r
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\n" ); document.write( "\n" ); document.write( "Plots y = \"sin%28theta%29+-+cos%28theta%29\" and y = \"sqrt%282%29\"\r
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\n" ); document.write( "There is a bunch of my lessons on solving trig equations in this site \r
\n" ); document.write( "\n" ); document.write( "    - Solving simple problems on trigonometric equations\r
\n" ); document.write( "\n" ); document.write( "    - Solving typical problems on trigonometric equations\r
\n" ); document.write( "\n" ); document.write( "    - Solving more complicated problems on trigonometric equations\r
\n" ); document.write( "\n" ); document.write( "    - Solving advanced problems on trigonometric equations\r
\n" ); document.write( "\n" ); document.write( "    - OVERVIEW of lessons on calculating trig functions and solving trig equations\r
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