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# C3 Maths Trig Help Watch

1. I was wondering if anyone can help which this question in C3. It would be much appreciated!

cosxsinx (cotx +tanx)

The book says it equals one but how?
Thanks
2. (Original post by dmurphy546)
I was wondering if anyone can help which this question in C3. It would be much appreciated!

cosxsinx (cotx +tanx)

The book says it equals one but how?
Thanks
Multiply out the brackets and write everything in terms of sinx and cosx
3. (Original post by dmurphy546)
I was wondering if anyone can help which this question in C3. It would be much appreciated!

cosxsinx (cotx +tanx)

The book says it equals one but how?
Thanks
cotx=cosx/sinx
tanx=sinx/cosx

and don't forget sinx*sinx+cosx*cosx=1
4. I got the bracket to equal 1 but was stuck on the other so you think it is better to just multiply it all out ?
5. Thanks for the replies by the way !
6. (Original post by coldfusion)
cotx=cosx/sinx
tanx=sinx/cosx

and don't forget sinx*sinx+cosx*cosx=1
I don't think I have all the rules for trig from my teacher so its making it pretty tough !
7. (Original post by dmurphy546)
I got the bracket to equal 1 but was stuck on the other so you think it is better to just multiply it all out ?
I don't think the bracket equals 1 it should equal by writing in terms of sinx and cos x and putting it over a common denominator of sinxcosx. If you multiply this by sinxcosx you get 1.
8. (Original post by Gemini92)
I don't think the bracket equals 1 it should equal by writing in terms of sinx and cos x and putting it over a common denominator of sinxcosx. If you multiply this by sinxcosx you get 1.
Thank you I get it now i was canceling the cos and sin like they were multiplied!

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