document.write( "Question 1161413: If cos x= -15/17 with x in quadrant III, find the exact value of sin 2x and the quadrant of 2x \n" ); document.write( "
Algebra.Com's Answer #784971 by MathLover1(20850)\"\" \"About 
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If \"cos+%28x%29=+-15%2F17+\"with \"x+\"in quadrant III, find the exact value of \"sin+%282x%29\" and the quadrant of \"2x\"\r
\n" ); document.write( "\n" ); document.write( "given:\r
\n" ); document.write( "\n" ); document.write( "\"cos+%28x%29=+-15%2F17+\"\r
\n" ); document.write( "\n" ); document.write( "find:\r
\n" ); document.write( "\n" ); document.write( "\"sin+%282x%29\" \r
\n" ); document.write( "\n" ); document.write( "use identity:\r
\n" ); document.write( "\n" ); document.write( "\"sin%282x%29=2sin%28x%29cos%28x%29\" ......substitute cos\r
\n" ); document.write( "\n" ); document.write( "\"sin%282x%29=2sin%28x%29%28-15%2F17%29+\"\r
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\n" ); document.write( "\n" ); document.write( " use \"sin%28x%29=sqrt%281-cos%5E2%28x%29%29\" to find sin\r
\n" ); document.write( "\n" ); document.write( "\"sin%28x%29=sqrt%281-%28-15%2F17%29+%5E2%29\"\r
\n" ); document.write( "\n" ); document.write( "\"sin%28x%29=sqrt%281-225%2F289%29\"\r
\n" ); document.write( "\n" ); document.write( "\"sin%28x%29=sqrt%28%28289-225%29%2F289%29\"\r
\n" ); document.write( "\n" ); document.write( "\"sin%28x%29=sqrt%2864%2F289%29\"\r
\n" ); document.write( "\n" ); document.write( "\"sin%28x%29\"\"8%2F17%29\"\r
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\n" ); document.write( "\n" ); document.write( "In Quadrant III, sine and cosine are negative:\r
\n" ); document.write( "\n" ); document.write( "\"sin%28x%29=-8%2F17\"\r
\n" ); document.write( "\n" ); document.write( "then\r
\n" ); document.write( "\n" ); document.write( "\"sin%282x%29=2%28-8%2F17%29%28-15%2F17%29+\"\r
\n" ); document.write( "\n" ); document.write( "\"sin%282x%29=240%2F289\"\r
\n" ); document.write( "\n" ); document.write( "\"2x=sin%5E-1%28240%2F289%29\"\r
\n" ); document.write( "\n" ); document.write( "\"2x=56.14\"° -> In Quadrant \"I\"\r
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