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# Compound angle watch

1. 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°).
2. (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°).
Ohhh nevermind i saw my mistake....b cannot be negative since it is already defined as 50° . So it is Cos(A+B) afterall
3. (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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