document.write( "Question 1131784: Find sin x/2, cos x/2, and tan x/2from the given information. sec x = 9/8, 270° < x < 360° \n" ); document.write( "
Algebra.Com's Answer #748471 by MathLover1(20850)\"\" \"About 
You can put this solution on YOUR website!
Find \"sin+%28x%2F2%29\", \"cos%28+x%2F2%29\", and\"+tan+%28x%2F2%29\" from the given information:\r
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\n" ); document.write( "\n" ); document.write( " \"sec+%28x+%29=+9%2F8\", \"270\"° < \"x\" < \"360\"° \r
\n" ); document.write( "\n" ); document.write( "\"sec+%28x+%29=+9%2F8=hypotenuse%2Fadjacent_side\"
\n" ); document.write( "\"hypotenuse=9\"
\n" ); document.write( "\"adjacent_+side=8\"
\n" ); document.write( "\"opposite_side=sqrt%289%5E2-8%5E2%29=sqrt%2881-64%29=sqrt%2817%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"sin+%28x%29=-sqrt%2817%29%2F9\" (in quadrant IV where \"sin%28x%29+%3C+0\")\r
\n" ); document.write( "\n" ); document.write( "\"cos%28+x%29=8%2F9\"\r
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\n" ); document.write( "\n" ); document.write( "Identities you need to use:\r
\n" ); document.write( "\n" ); document.write( "\"sin+%28x%2F2%29\"= ± \"sqrt%28%281-cos+%28x%29%29%2F2%29\"\r
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\n" ); document.write( "\n" ); document.write( "choose positive root because \"%28x%2F2%29\" is in quadrant II where\"+sin%28x%29+%3E+0\"\r
\n" ); document.write( "\n" ); document.write( "\"sin+%28x%2F2%29\"= ± \"sqrt%28%281-cos+x%29%2F2%29=sqrt%28%281-8%2F9%29%2F2%29=sqrt%281%2F18%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"cos+%28x%2F2%29\"= ± \"sqrt%28%281%2Bcos%28+x%29%29%2F2%29\"\r
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\n" ); document.write( "\n" ); document.write( "choose negative root because \"%28x%2F2%29\" is in quadrant II where \"cos%28x%29%3C+0\"\r
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\n" ); document.write( "\n" ); document.write( "How to check answers with calculator:\r
\n" ); document.write( "\n" ); document.write( "\"sec+%28x%29=9%2F8\"
\n" ); document.write( "\"cos+%28x%29=8%2F9\"\r
\n" ); document.write( "\n" ); document.write( "\"cos%5E-1%288%2F9%29\"\"0.47588225\" radians ≈\"27.27\"° (reference angle in specified quadrant IV)\r
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\n" ); document.write( "\n" ); document.write( "standard position of angle=\"360-27.27%B0=332.73\"°
\n" ); document.write( "\"x%2F2=332.73%2F2=166.37\"º\r
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\n" ); document.write( "\n" ); document.write( "reference angle=\"180-166.37=13.63\"º\r
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\n" ); document.write( "\n" ); document.write( "\"sin+%28x%2F2%29=sin+%2813.63%29\"\"0.2357\".......(in quadrant II where \"sin%28x%29+%3E+0\")\r
\n" ); document.write( "\n" ); document.write( "and above we have
\n" ); document.write( "\"sin+%28x%2F2%29=sqrt%281%2F18%29=0.2357\".....which confirms our solution\r
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\n" ); document.write( "\n" ); document.write( "you can check \"cos+%28x%2F2%29\" and tan \"%28x%2F2%29\" in the same way \r
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