document.write( "Question 1109042: Sec A + tan A =2 find sin A + cos A ?\r
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Algebra.Com's Answer #724067 by KMST(5328)\"\" \"About 
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\"sec%28A%29%2Btan%28A%29=2\"
\n" ); document.write( "\"1%2Fcos%28A%29%2Bsin%28A%29%2Fcos%28A%29=2\"
\n" ); document.write( "\"%281%2Bsin%28A%29%29%2Fcos%28A%29=2\"
\n" ); document.write( "\"1%2Bsin%28A%29=2cos%28A%29\"
\n" ); document.write( "\"sin%28A%29=2cos%28A%29-1\"
\n" ); document.write( "Let us say \"cos%28A%29=x\" .
\n" ); document.write( "Then,
\n" ); document.write( "\"sin%28A%29=%22+%22+%2B-+sqrt%281-x%5E2%29\"
\n" ); document.write( "Substituting those expressions for sine and cosine,
\n" ); document.write( "\"%22+%22+%2B-+sqrt%281-x%5E2%29=2x-1\"
\n" ); document.write( "Squaring both sides,
\n" ); document.write( "\"1-x%5E2=4x%5E2%2B4x%2B1\"
\n" ); document.write( "\"0=4x%5E2%2B4x%2B1%2Bx%5E2-1\"
\n" ); document.write( "\"0=5x%5E2%2B4x\"
\n" ); document.write( "\"%285x-4%29x=0%0D%0AThe+solutions+are+%7B%7B%7Bx=0\" and \"x=4%2F5=0.8\" ,
\n" ); document.write( "which translate into \"cos%28x%29=0\" and \"cos%28x%29=4%2F5=0.8\" .
\n" ); document.write( "\"cos%28x%29=0\" is not a solution of the original equation,
\n" ); document.write( "because it would make \"sec%28A%29\" and \"tan%28A%29\" undefined.
\n" ); document.write( "For \"cos%28A%29=x=4%2F5=0.8\" , \"sec%28A%29=1%2F0.8=1.25\" , and
\n" ); document.write( "\"sin%28A%29=%22+%22+%2B-+sqrt%281-x%5E2%29=%22+%22+%2B-+3%2F5=%22+%22+%2B-+0.6\" .
\n" ); document.write( "\"sin%28A%29=-0.6\" would make \"tan%28A%29=-0.6%2F0.8=-0.75\" and \"sec%28A%29%2Btan%28A%29=1.25-0.75=0.5\" so that is not a solution either.
\n" ); document.write( "\"system%28cos%28A%29=0.8%2Csin%28A%29=0.6%29\" makes \"sec%28A%29%2Btan%28A%29=1.25%2B0.75=2\"and is the solution.
\n" ); document.write( "So \"sin%28A%29%2Bcos%28A%29=0.8%2B0.6=highlight%281.4%29\" .\r
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