document.write( "Question 864456: I cannot for the life of me figure these out, please help!\r
\n" ); document.write( "\n" ); document.write( "given sin a = 4/5 in quadrant I and cos ß = 12/13 in quadrant II find cos a+ß\r
\n" ); document.write( "\n" ); document.write( "given cos a = -24/25 in quadrant II and sin ß = -5/13 in quadrant III, find sin (a+ß) \n" ); document.write( "

Algebra.Com's Answer #521008 by ewatrrr(24785) $\"\"$ $\"About$

You can put this solution on YOUR website!


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document.write( "Hi
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document.write( "given sin a = 4/5 in quadrant I and cos ß = ???12/13 in quadrant II find cos a+ß \r
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document.write( "given cos a = -24/25 in quadrant II ⇒ sin a = 7/25    
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document.write( "and sin ß = -5/13 in quadrant III   ⇒ cos ß = -12/13
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document.write( "cos(a + ß) = cos a cos ß  -  sin a sin ß     (substitute appropriate values)
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document.write( "           = (-24/25)(-12/13) - (7/25)(-5/13)   
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document.write( "           = (24*12+35)/25*13 \n" );
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