document.write( "Question 1154166: Evaluate Sec 660degrees + Cot 405degrees without using a calculator. Please show steps thanks you! \n" ); document.write( "
Algebra.Com's Answer #776545 by MathLover1(20850)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "\"sec%28+660%29+%2B+cot+%28405%29\"..........express \"sec%28+660%29\" with sin and cos\r
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\n" ); document.write( "\n" ); document.write( "=\"1%2Fcos%28+660%29+%2B+cot%28405%29\"..use identity: \"cos%28x%29=sin%2890-x%29\"..since your \"x=660\"\r
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\n" ); document.write( "\n" ); document.write( "=\"1%2Fsin%2890-660%29+%2B+cot%28405%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"1%2Fsin%28-570%29+%2B+cot%28405%29\"...........use the following property : \"sin+%28-x+t%29=-+sin+%28x+%29\"\r
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\n" ); document.write( "\n" ); document.write( "=\"-1%2Fsin%28570%29+%2B+cot%28405%29\"\r
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\n" ); document.write( "\n" ); document.write( "rewrite \"sin%28570%29\" .......... apply the periodicity of sin : \"sin%28570%29=sin%28x%2B360%2Ak%29=sin%28x%29\"\r
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\n" ); document.write( "\n" ); document.write( "so, \"sin%28570%29+=sin%28210%29+\"\r
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\n" ); document.write( "\n" ); document.write( "=\"-1%2Fsin%28210%29+%2B+cot%28405%29\"................rewrite the angles for \"cot%28405=360%2B45%29\"=\"cot%2845%29\"\r
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\n" ); document.write( "\n" ); document.write( "=\"-1%2Fsin%28210%29+%2B+cot%2845%29\"......write \"sin+%28210+%29\" as \"sin+%28180+%2B30+%29\"\r
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\n" ); document.write( "\n" ); document.write( "using the summation identity : \"sin+%28x%2By+%29=+sin++%28x+%29+cos+%28y+%29%2B+cos+%28x+%29+sin+%28y+%29\"\r
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\n" ); document.write( "\n" ); document.write( "so you have \"sin+%28180+%2B30+%29=+sin++%28180+%29+cos+%2830+%29%2B+cos+%28180+%29+sin+%2830+%29\"\r
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\n" ); document.write( "\n" ); document.write( "now use the following trivial identities:\r
\n" ); document.write( "\n" ); document.write( "\"sin++%28180+%29=0\"\r
\n" ); document.write( "\n" ); document.write( "\"cos+%28180+%29=-1\"\r
\n" ); document.write( "\n" ); document.write( "\"sin+%2830+%29=1%2F2\"\r
\n" ); document.write( "\n" ); document.write( "\"cos+%2830+%29=sqrt%283%29%2F2\"\r
\n" ); document.write( "\n" ); document.write( "then you have \"sin+%28180+%2B30+%29=+0%2A++%28sqrt%283%29%2F2+%29%2B+%28-1+%29+%281%2F2+%29=-1%2F2\"\r
\n" ); document.write( "\n" ); document.write( "and \"cot%2845%29=cos%2845%29%2Fsin%2845%29=%281%2Fsqrt%282%29%29+%2F%281%2Fsqrt%282%29%29=1+\"\r
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\n" ); document.write( "\n" ); document.write( "so, you have:\r
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\n" ); document.write( "\n" ); document.write( "=\"-1%2F%28-1%2F2%29+%2B+1\"\r
\n" ); document.write( "\n" ); document.write( "=\"2+%2B+1\"\r
\n" ); document.write( "\n" ); document.write( "=\"3\"\r
\n" ); document.write( "\n" ); document.write( "=> \"sec%28+660%29+%2B+cot+%28405%29=3\"\r
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