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chrisdbest
 one year ago
Rewrite with only sin x and cos x.
cos 3x
(A) cos x  4 cos x sin2x
(B)sin3x + 2 sin x cos x
(C)sin2x + 2 sin x cos x
(D)2 sin2x cos x  2 sin x cos x
chrisdbest
 one year ago
Rewrite with only sin x and cos x. cos 3x (A) cos x  4 cos x sin2x (B)sin3x + 2 sin x cos x (C)sin2x + 2 sin x cos x (D)2 sin2x cos x  2 sin x cos x

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welshfella
 one year ago
Best ResponseYou've already chosen the best response.0Hint cos 3x = cos(2x + x)

chrisdbest
 one year ago
Best ResponseYou've already chosen the best response.0I have a headache from a slip and fall accident and just don't feel like working. I will medal you if you have the correct answer.

welshfella
 one year ago
Best ResponseYou've already chosen the best response.0but I dont think we can use that anyway because cos ( a + b) = cosa cosb  sina sinb

chrisdbest
 one year ago
Best ResponseYou've already chosen the best response.0So can someone please tell me the answer

welshfella
 one year ago
Best ResponseYou've already chosen the best response.0Its not C because that simplifies to sin 2x + sin2x = 0

chrisdbest
 one year ago
Best ResponseYou've already chosen the best response.0I know it's not D because I chose that and it was wrong

welshfella
 one year ago
Best ResponseYou've already chosen the best response.0I cant convert cos 3x into any of the options . I think there might be an error in the question. I'll plug in x = 20 degrees and see if any of them work out to 0.5 (because cos 60 = 0.5)

welshfella
 one year ago
Best ResponseYou've already chosen the best response.0 sin 60 + 2 cos 20 sin 20 = 0.2232 not that one

welshfella
 one year ago
Best ResponseYou've already chosen the best response.0nor A  none of them equal cos 3x

welshfella
 one year ago
Best ResponseYou've already chosen the best response.0thers a problem with the question

chrisdbest
 one year ago
Best ResponseYou've already chosen the best response.0That's the beauty of Virtual School

LynFran
 one year ago
Best ResponseYou've already chosen the best response.0Try https://www.symbolab.com/solver/trigonometricidentitycalculator

chrisdbest
 one year ago
Best ResponseYou've already chosen the best response.0I know it's not D or B, because I just got it wrong and can't do it over again. I have been told it's not A or C by an elite, and I KEEP GETTING THE QUESTION WRONG!!!!
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