document.write( "Question 1180320: If sin α = 4/5 and cos β = -5/13 for α in Quadrant I and β in Quadrant II, find cos(α - β) \n" ); document.write( "
Algebra.Com's Answer #809946 by mananth(16946)\"\" \"About 
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cos(α - β)= \"cos%28alpha%29cos%28beta%29+%2Bsin%28alpha%29sin%28beta%29\"\r
\n" ); document.write( "\n" ); document.write( "sin α = 4/5 in quadrant I cos α = 3/5.\r
\n" ); document.write( "\n" ); document.write( "cos β = -5/13 quadrant II means sin β = 12/13.\r
\n" ); document.write( "\n" ); document.write( "Plug the values
\n" ); document.write( " (3/5)(-5/13) + (4/5)((12/13)\r
\n" ); document.write( "\n" ); document.write( "(-3/13) + (48/85)\r
\n" ); document.write( "\n" ); document.write( "(-15+48)/85\r
\n" ); document.write( "\n" ); document.write( "33/85
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