document.write( "Question 1070794: suppose that sine A=(3/5),cos B=(5/13)and both A and B are in the first quadrant,find sine (A+B) \n" ); document.write( "
Algebra.Com's Answer #685847 by ikleyn(52873)\"\" \"About 
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\n" ); document.write( "suppose that sine A=(3/5),cos B=(5/13)and both A and B are in the first quadrant,find sine (A+B)
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document.write( "Use the \"addition formula for sine\":\r\n" );
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document.write( "sin(A + B) = sin(A)*cos(B) + cos(A)*sin(B)     (*)\r\n" );
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document.write( "It is one of fundamental formulas of Trigonometry. You can find it in any serious Trigonometry textbook. \r\n" );
document.write( "Also see the lesson  Addition and subtraction formulas  in this site.\r\n" );
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document.write( "To use it, you must know cos(A) and sin(B) in addition to given sin(A) = 3/5  and cos(B) = 5/13.\r\n" );
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document.write( "It is easy to calculate:\r\n" );
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document.write( "1)  cosA) = \"sqrt%281-sin%5E2%28A%29%29\" = \"sqrt%281-%283%2F5%29%5E2%29\" = \"sqrt%281-9%2F25%29\" = \"sqrt%2816%2F25%29\" = \"4%2F5\".\r\n" );
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document.write( "2)  sin(B) = \"sqrt%281-cos%5E2%28B%29%29\" = \"sqrt%281-%285%2F13%29%5E2%29\" = \"sqrt%281-25%2F169%29\" = \"sqrt%28144%2F169%29\" = \"12%2F13\".\r\n" );
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document.write( "Now you have EVERYTHING to use the formula (*):\r\n" );
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document.write( "sin(A + B) = \"%283%2F5%29%2A%285%2F13%29+%2B+%284%2F5%29%2A%2812%2F13%29\" = \"15%2F65+%2B+48%2F65\" = \"63%2F65\".\r\n" );
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\n" ); document.write( "\n" ); document.write( "For similar solved problems see 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( "in this site.\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
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this online textbook under the topics
\n" ); document.write( "\"Trigonometry. Formulas for trigonometric functions\" and \"Trigonometry: Solved problems\". \r
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