Please help

[MBBS]

Hey if someone could solve this for me then create a mirror question I would appreciate.


     5 sin 3x cos 3x cos 6x            5
    -----------------------     =   --      tan 12x
      2 cos²6x -1              4

[pi]

Hey if someone could solve this for me then create a mirror question I would appreciate.


     5 sin 3x cos 3x cos 6x            5
    -----------------------     =   --      tan 12x
      2 cos²6x -1          4

I don't understand the fraction... is the 4 supposed to be under the 5?

[MBBS]

Yes. Sorry I can't format it properly.

[brightsky]

Look at the denominator.

Recall the double angle formula:



Now look at the numerator.

Recall that:

So

So the numerator becomes:

Use the double angle formula again:



The numerator becomes

Couple that with the denominator:

[MBBS]

That made zero sense to me. I know the double angle formulas etc, but get totally lost when it's (3x) (6x) etc. Is there any resources for this kind of stuff?

[MBBS]

Hmmm... will try that.

[brightsky]

That made zero sense to me. I know the double angle formulas etc, but get totally lost when it's (3x) (6x) etc. Is there any resources for this kind of stuff?

We have the general formula

If we "sub" 3x into that formula, it becomes

Same deal for sine.

[MBBS]

^^^ Shit man thanks!

Then what do I do after i get to that?

Fuck I'm useless at this topic.