document.write( "Question 898329: complete: sin 225 cos 90 - cos 225 sin 90 = \n" ); document.write( "

Algebra.Com's Answer #544747 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"+sin%28+225+%29+%2A+cos%28+90+%29+-+cos%28+225+%29+%2A+sin%28+90+%29+\"$
\n" ); document.write( " $\"+cos%28+90+%29+=+0+\"$
\n" ); document.write( " $\"+sin%28+90+%29+=++1+\"$
\n" ); document.write( "The problem reduces to:
\n" ); document.write( " $\"+-+cos%28+225+%29+\"$
\n" ); document.write( " $\"+-cos%28+180+%2B+45+%29+\"$
\n" ); document.write( "The cosine is negative in the 3rd quadrant, so
\n" ); document.write( " $\"+-%28+-+sqrt%282%29+%2F+2+%29+\"$
\n" ); document.write( " $\"+sqrt%282%29+%2F+2+\"$
\n" ); document.write( " \n" ); document.write( "

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