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# C3 Trigonometry question (C2 knowledge)

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1. 4cot2x + sec2x= 5

x= theta

domain: 0 </= x </= 360

I worked out that cosx= 1/2 and 1

The answer is x= 0, 180, 360, 60, 120, 240, 300 (degrees).

How do you get 120, 180 and 240? Is there a method that you use to make sure you have every root?

Thanks
2. (Original post by Jellyxx)
4cot2x + sec2x= 5

x= theta

domain: 0 </= x </= 360

I worked out that cosx= 1/2 and 1

The answer is x= 0, 180, 360, 60, 120, 240, 300 (degrees).

How do you get 120, 180 and 240? Is there a method that you use to make sure you have every root?

Thanks
I think you have miscopied the equation..

Ignoring that though, did you have cos^2 x =1 or 0.25?

If so you forgot the ± when you square rooted.

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