document.write( "Question 967036: Evaluate: tan^2 (-405°) - sec^2 (-405°) + cos 900°\r
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Algebra.Com's Answer #591023 by MathLover1(20850) $\"\"$ $\"About$

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$\"tan%5E2+%28-405%29+-+sec%5E2+%28-405%29+%2B+cos+900\"$ ° =?\r
\n" ); document.write( "\n" ); document.write( " $\"tan%5E2+%28-405%29+=+tan%5E2+%28-45%29+\"$ °\r
\n" ); document.write( "\n" ); document.write( " $\"tan%5E2+%28-45%29=+sin%5E2+%28-45%29%2Fcos%5E2+%28-45%29\"$ °\r
\n" ); document.write( "\n" ); document.write( "since $\"sin%5E2+%28-45%29=1%2F2\"$ and $\"cos%5E2+%28-45%29=1%2F2\"$ we have $\"tan%5E2+%28-45%29+=%281%2F2%29%2F%281%2F2%29=1\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"sec%5E2+%28-405%29+=+1%2Fcos%5E2+%28-45%29\"$ \r
\n" ); document.write( "\n" ); document.write( "since $\"cos%5E2+%28-45%29=1%2F2\"$ => $\"1%2Fcos%5E2+%28-45%29=2\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"cos+%28900%29+=cos+%28180%29=-1\"$ \r
\n" ); document.write( "\n" ); document.write( "so,

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\n" ); document.write( "\n" ); document.write( "then, your answer is: $\"tan%5E2+%28-405%29+-+sec%5E2+%28-405%29+%2B+cos%28+900%29=-2\"$ \r
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