document.write( "Question 1176584: Find cos(s - t) given that cos s = - 1/6, with s in quadrant III, and cos t=-3/5 with t in quadrant III \n" ); document.write( "

Algebra.Com's Answer #803736 by Edwin McCravy(20059) $\"\"$ $\"About$

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document.write( "First you draw a picture of angle s in quadrant III, and draw a perpendicular\r\n" );
document.write( "from the end of the terminal side up to the x-axis.\r\n" );
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document.write( "You are given cos(s) = -1/6. You know that cosine = adjacent/hypotenuse,\r\n" );
document.write( "which is x/r, so we label the x value as the numerator of -1/6, which\r\n" );
document.write( "is -1, and we label the hypotenuse (the terminal side) as the denominator\r\n" );
document.write( "of -1/6, which is 6. (The hypotenuse or terminal side is always taken\r\n" );
document.write( "positive.\r\n" );
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document.write( "We use the Pythagorean theorem to find the value of y:\r\n" );
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document.write( "Since y goes down from the x-axis we give it a negative sign.\r\n" );
document.write( "We label the opposite side, which is y, as -√35\r\n" );
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document.write( "We will need the sine and cosine of s,\r\n" );
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document.write( " which is given, and\r\n" );
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document.write( "The same way, draw the angle t, and get this graph:\r\n" );
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document.write( "We will need the sine and cosine of t,\r\n" );
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document.write( " which is given, and\r\n" );
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document.write( "Now we use the formula for \r\n" );
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document.write( "Edwin

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