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    The question requires the greatest value of the expression and the value of A between 0 and 360°.
    Question : CosACos50°-SinASin50°
    So this is clearly the expanded form of Cos (A+/- B) but since theres a -ve sign , it should be Cos( A+B).
    However since Sin(-x) = - Sin(x), Cos(A-B) becomes valid as well.
    Since the greatest value is required, the 4th quadrant fits the requirement when Sin(-x) and Cos(+x) and the highest value is 360°.
    Therefore Cos(360°-50°) = Cos(310°).
    The textbook answer is Cos(310°+50°)=1
    Can anyone please explain?
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    (Original post by Bilbao)
    The question requires the greatest value of the expression and the value of A between 0 and 360°.
    Question : CosACos50°-SinASin50°
    So this is clearly the expanded form of Cos (A+/- B) but since theres a -ve sign , it should be Cos( A+B).
    However since Sin(-x) = - Sin(x), Cos(A-B) becomes valid as well.
    Since the greatest value is required, the 4th quadrant fits the requirement when Sin(-x) and Cos(+x) and the highest value is 360°.
    Therefore Cos(360°-50°) = Cos(310°).
    The textbook answer is Cos(310°+50°)=1
    Can anyone please explain?
    Ohhh nevermind i saw my mistake....b cannot be negative since it is already defined as 50° . So it is Cos(A+B) afterall
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    (Original post by Bilbao)
    Ohhh nevermind i saw my mistake....b cannot be negative since it is already defined as 50° . So it is Cos(A+B) afterall
    yes.
 
 
 
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