document.write( "Question 823644: Let sin s = (-1/4), with s in quadrant 4 and cos t = (-4/5), with t in quadrant 2.
\n" ); document.write( "Find sin(s+t) and explain. \n" ); document.write( "

Algebra.Com's Answer #495668 by josmiceli(19441) $\"\"$ $\"About$

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The angle whose sin is $\"+.25+\"$ is $\"+14.478+\"$ degrees
\n" ); document.write( " $\"+360+-+14.478+=+345.522+\"$ which places it in the 4th quadrant
\n" ); document.write( " $\"+s+=+345.522+\"$
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\n" ); document.write( "The angle whose cosine is $\"+4%2F5+\"$ is $\"+36.870+\"$ degrees
\n" ); document.write( " $\"+180+-+36.870+=+143.130+\"$ which places it in the 2nd quadrant
\n" ); document.write( " $\"+t+=+143.130+\"$
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\n" ); document.write( " $\"+sin%28+s+%2B+t+%29+=+sin%28+345.522+%2B+143.130+%29+\"$
\n" ); document.write( " $\"+sin%28+s+%2B+t+%29+=+sin%28+488.652+%29+\"$
\n" ); document.write( " $\"+sin%28+s+%2B+t+%29+=+sin%28+3%2A180+-+488.652+%29+\"$
\n" ); document.write( "( this shows that the angle ends up in the 2nd quadrant )
\n" ); document.write( " $\"+sin%28+s+%2B+t+%29+=+sin%28+540+-+488.652+%29+\"$
\n" ); document.write( " $\"+sin%28+s+%2B+t+%29+=+sin%28+51.348+%29+\"$
\n" ); document.write( " $\"+sin%28+51.348+%29+=+.781+\"$
\n" ); document.write( "( note that the sin is positive in the 2nd quadrant\r
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