document.write( "Question 329736: How do I use reference angles to find the exact value of sin 240 DEG? I need to know the steps and the answers. I can't find it in my reading or my notes. \n" ); document.write( "

Algebra.Com's Answer #236331 by texttutoring(324) $\"\"$ $\"About$

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240 is 60 degrees more than 180 degrees.\r
\n" ); document.write( "\n" ); document.write( "On the grid with a unit circle, this would put it in the lower left quadrant.\r
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\n" ); document.write( "\n" ); document.write( "The reference angle would be 60 degrees. You always start at 0 degrees and move around in a counter-clockwise direction.\r
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\n" ); document.write( "\n" ); document.write( "Knowing that the reference angle is 60 degrees, you can then draw a triangle, which will be a special triangle of 30-60-90, which you should know the ratios for.\r
\n" ); document.write( "\n" ); document.write( "The sin of 60 is sqrt(3)/2, so the sine of 240 will be -sqrt(3)/2.\r
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\n" ); document.write( "\n" ); document.write( "Recall the principle of CAST (which specifies which quadrants have positive trig values).\r
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\n" ); document.write( "\n" ); document.write( "Hope this makes some sense. It would be easier if I could draw a picture. If you need some clarifications, just let me know. \n" ); document.write( "

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