document.write( "Question 1181125: Given: cos A = 3/5, tan B = 12/5, A is in Quadrant 1 and is in Quadrant 3
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Algebra.Com's Answer #810968 by ikleyn(52794)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "            The numbers and calculations in the post by @mananth are INCORRECT.\r
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\n" ); document.write( "\n" ); document.write( "            Therefore, for your safety,  IGNORE  his  (or her)  post.\r
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\n" ); document.write( "\n" ); document.write( "            I came to bring a correct solution.\r
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document.write( "cos A = \"3%2F5\",  A is in Quadrant 1 \r\n" );
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document.write( "sin A = \"sqrt%281-cos%5E2%28A%29%29\" = \"sqrt%281-%283%2F5%29%5E2%29\" = \"sqrt%281-%289%2F25%29%29\" = \"sqrt%2816%2F25%29%29\" = \"4%2F5\", \r\n" );
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document.write( "cos A = \"3%2F5\", tan A = \"4%2F3\"\r\n" );
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document.write( "tan B = \"12%2F5\", quadrant III   ( ! not quadrant IV, as @mananth mistakenly wrote ! )\r\n" );
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document.write( "tan B = \"12%2F5\", sin B = \"-12%2F13\", cos B = \"-5%2F13\"\r\n" );
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document.write( "sin (A + B) = sin(A)cos(B) + cos(A)sin(B) = \"%284%2F5%29%28-5%2F13%29\" + \"%283%2F5%29%28-12%2F13%29\" = \"-20%2F65\" - \"36%2F65\" = \"-56%2F65\".\r\n" );
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document.write( "sin(A − B) = sin(A)*cos(B) − cos(A)*sin(B) = \"%284%2F5%29%28-5%2F13%29\" - \"%283%2F5%29%28-12%2F13%29\" = \"-20%2F65\" + \"36%2F65\" = \"16%2F65\".\r\n" );
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document.write( "cos(A + B) = cos A cos B − sin A sin B \r\n" );
document.write( "cos(A − B) = cos A cos B + sin A sin B \r\n" );
document.write( "sin(A + B) = sin A cos B + cos A sin B \r\n" );
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document.write( "Plug values and continue\r\n" );
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\n" ); document.write( "\n" ); document.write( "To see many other similar solved problems on calculating trig functions,  look into the lessons \r
\n" ); document.write( "\n" ); document.write( "    - Calculating trigonometric functions of angles\r
\n" ); document.write( "\n" ); document.write( "    - Advanced problems on calculating trigonometric functions of angles\r
\n" ); document.write( "\n" ); document.write( "    - Evaluating trigonometric expressions \r
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\n" ); document.write( "\n" ); document.write( "Also,  you have this free of charge online textbook in ALGEBRA-II in this site\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this online textbook under the topic  \"Trigonometry: Solved problems\". \r
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\n" ); document.write( "\n" ); document.write( "Save the link to this textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-II
\n" ); document.write( "https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson\r
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