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Use the given information to find the exact value of the expression. sin α =21/29 , α lies in quadrant IV, and cos β =-4/11 , β lies in quadrant III Find cos(α+β).
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Use the given information to find the exact value of the expression. sin α =21/29 , α lies in quadrant IV, and cos β =-4/11 , β lies in quadrant III Find cos(α+β).
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Jan 11, 2017
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Use the given information to find the exact value of the expression.
sin α =21/29 , α lies in quadrant IV, and cos β =-4/11 , β lies in quadrant III Find cos(α+β).
Mathematics
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RobinJoe
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Hello,
sin α =21/29 and α lies in quadrant IV ==>cos α =√(1²-(21/29)²)=20/29.
cos β =-4/11 , β lies in quadrant III ==> sin β =-√(1²-(4/11)²)=-√105 /11
cos(α+β)=cos α cos β- sin α sin β
=20/29*(-4/11)+21/29*√105 / 11
=(-80+21√105)/(11*29)
Peter Wilson
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Jan 16, 2017
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