Triple angle proof

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Skelly4444

Junior Member
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Apr 4, 2019
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How can (cos3x / sinx) + (sin3x / cosx) be identically equivalent to 2cot2x

I have tried rewriting everything but cannot seem to get anywhere with this?

Any advice would be greatly appreciated.
 
Skelly4444 said:
How can (cos3x / sinx) + (sin3x / cosx) be identically equivalent to 2cot2x

I have tried rewriting everything but cannot seem to get anywhere with this?

Any advice would be greatly appreciated.
Click to expand...
I would first combine it into one fraction. Then I'd recognize something familiar. Something different might work better for you, but we'll know that after we've seen your work.
 
Thanks for responding, I've actually managed to work it out by using common denominator of sinxcosx and then recognising that the top of the fraction is the addition format for cos(3x - x) which obviously equates to cos2x. From here, it was quite straight forward.
 
Skelly4444 said:
Thanks for responding, I've actually managed to work it out by using common denominator of sinxcosx and then recognising that the top of the fraction is the addition format for cos(3x - x) which obviously equates to cos2x. From here, it was quite straight forward.
Click to expand...
Nice work !!
 
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