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Hira S.

asked • 07/07/19

Write −6sin(8t)+5cos(8t) in the form Asin(Bt+ϕ) using sum or difference formulas. −6sin(8t)+5cos(8t) =

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Thien D. answered • 07/08/19

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Doug C.

Acos(φ) = -6, Asin(φ) = 5 Based on the above and since A is positive, it feels like φ must be a 2nd quadrant angle (sin positive and cos negative).
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07/08/19

Thien D.

Good point! Thanks for the comment :)
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07/08/19

Ben Z.

How come we need to change the angle from -38.81 to 149.19, quadrant 2 to 4?
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08/06/20

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