document.write( "Question 1054631: use the given information to find:
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\n" ); document.write( "the quadrant of s+t\r
\n" ); document.write( "\n" ); document.write( "sin s= 1/7 QII
\n" ); document.write( "sin t= -6/7 QIV \n" ); document.write( "
Algebra.Com's Answer #669816 by ikleyn(52787)\"\" \"About 
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.
\n" ); document.write( "use the given information to find:
\n" ); document.write( "sin(s+t)
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\n" ); document.write( "\n" ); document.write( "sin s= 1/7 QII
\n" ); document.write( "sin t= -6/7 QIV
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document.write( "Stap by step:\r\n" );
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document.write( "1.  sin(s)= 1/7 QII  --->  cos(s) = \"-sqrt%281-sin%5E2%28s%29%29\" = \"-sqrt%281-%281%2F7%29%5E2%29\" = \"-sqrt%2848%29%2F7\" = \"-%284%2Asqrt%283%29%29%2F7\".\r\n" );
document.write( "           The sign is \"-\" at sqrt since cosine is negative in QII.\r\n" );
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document.write( "2.  sin(t)= -6/7 QIV  --->  cos(t) = \"sqrt%281-sin%5E2%28t%29%29\" = \"sqrt%281-%28-6%2F7%29%5E2%29\" = \"sqrt%2813%29%2F7\" = \"%28sqrt%2813%29%29%2F7\".\r\n" );
document.write( "           The sign is \"+\" at sqrt since cosine is positive in QIV.\r\n" );
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document.write( "3.   Now  sin(s+t) = sin(s)*cos(t) + cos(s)*sin(t) = \"%281%2F7%29%2A%28sqrt%2813%29%2F7%29+%2B+%28-4%2Asqrt%283%29%2F7%29%2A%28-6%2F7%29\" =  \"%28sqrt%2813%29+%2B+24%2Asqrt%283%29%29%2F49\".\r\n" );
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document.write( "4.   Next cos(s+t) = cos(s)*cos(t) - sin(s)*sin(t) = \"%28-4%2Asqrt%283%29%2F7%29%2A%28sqrt%2813%29%2F7%29+-+%281%2F7%29%2A%28-6%2F7%29\" =  \"%28-4%2Asqrt%283%29%2Asqrt%2813%29+%2B+6%29%2F49\" = \"%286-4%2Asqrt%2839%29%29%2F7\".\r\n" );
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document.write( "5.  Finally,  tan(s+t) = \"sin%28s%2Bt%29%2Fcos%28s%2Bt%29\" = \"%28sqrt%2813%29+%2B+24%2Asqrt%283%29%29%2F%286-4%2Asqrt%2839%29%29\".\r\n" );
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document.write( "6.  From (3), sin(s+t) is positive;  from (4), cos(s+t) is negative.  Hence, s+t lies in QII.\r\n" );
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\n" ); document.write( "\n" ); document.write( "For detailed solution of similar problem see the lessons \r
\n" ); document.write( "\n" ); document.write( "    - Calculating trigonometric functions of angles, Problems 5 and 7, \r
\n" ); document.write( "\n" ); document.write( "    - Advanced problems on calculating trigonometric functions of angles, Problem 1 \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 topic \"Trigonometry: Solved problems\".\r
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