Question

Verify the Trigonometry Identity. (cos4x+cos2x) / (sin4x+sin2x) = cot3x. Much Appreciated! @@QUESTION ON HOLD@@

Answer 1

Do you know how to apply the double angle formula?

Answer 2

Kind of...

Answer 3

Show me your attempt.

Answer 4

@LXelle Is there a trig identity for cos4x? O_O

Answer 5

Did I mention double angle?

Answer 6

Yes

Answer 7

\[\cos(4x)=\cos ^{2}(x)-\sin ^{2}(2x)=2\cos ^{2}(2x)-1=1-2\sin ^{2}(2x) \]

Answer 8

\[\sin(4x)=2\sin(2x)\cos(2x)\]

Answer 9

\[1-2\sin ^{2}(2x)+1-2\sin ^{2}(x) / 2\sin(2x)\cos(2x)+2\sin(x)\cos(x) ??\]

Answer 10

How about using product rule for the numerator and denominator?

Answer 11

like sinUsinV=1 / 2 [ cos (u-v) - cos (u + v) ]?

Answer 12

yeah yeah something like that.

Answer 13

Going to try it then, putting this question on hold again while I work on another attempt.

Answer 14

In your case the numerator would be 2 cos ((4x+2x)/2) cos ((4x-2x)/2)