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shaqadry
 3 years ago
how to solve 3 sin^2 2x + 2 cos 2x  2 = 0
shaqadry
 3 years ago
how to solve 3 sin^2 2x + 2 cos 2x  2 = 0

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Azteck
 3 years ago
Best ResponseYou've already chosen the best response.0\[3\sin^{2}(2x)= 3(1\cos^{2}(2x))\] \[=33\cos^2(2x)\]  \[33\cos^2(2x)+2cos(2x)2=0\] Collect like terms and move everything to the RHS \[3\cos^2(2x)2cos(2x)1=0\] Let u=cos(2x) \[3u^22u1=0\] Solve the quadratic.

shaqadry
 3 years ago
Best ResponseYou've already chosen the best response.0i dont get it, what happen to sin^2 2x?

Azteck
 3 years ago
Best ResponseYou've already chosen the best response.0Yeah I just made sin^2(2x) in terms of cos(2x).

Azteck
 3 years ago
Best ResponseYou've already chosen the best response.0So could you solve that quadratic and then after you have the values of u, bring back the cos(2x) by replacing u with cos(2x).

Azteck
 3 years ago
Best ResponseYou've already chosen the best response.0Then after you've done that, solve normally as if it were cos(x) and then after you get the angles, divide by 2 because you're finding x, not 2x.

Azteck
 3 years ago
Best ResponseYou've already chosen the best response.0If you're unclear about what you're supposed to do, let me know.

shaqadry
 3 years ago
Best ResponseYou've already chosen the best response.0okay thanks! i really didnt know how to solve that part bcs it has 2x

shaqadry
 3 years ago
Best ResponseYou've already chosen the best response.0wait i'll try and calculate the angle

shaqadry
 3 years ago
Best ResponseYou've already chosen the best response.0the angles i got are 0, 54.75, 125.25, 180, 234.75, 305. 25 and 360

Azteck
 3 years ago
Best ResponseYou've already chosen the best response.0Awesome work. That's pretty much all of them. I think you need to work on your rounding up. Because for some of the angles, I got either 0.01 more or less than your angles.

Azteck
 3 years ago
Best ResponseYou've already chosen the best response.0Ah I see, you rounded up before dividing by 2. That's okay. You're still correct. I just prefer to round up at the end result.
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