# Proving Identities

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#1
Question 7b I've spent ages going round in circles but I cant seem to prove it. The answer to part a btw is 1-3tan^2 theta
http://imgur.com/a/kcX0qsK
0
4 months ago
#2
(Original post by Y12_FurtherMaths)
Question 7b I've spent ages going round in circles but I cant seem to prove it. The answer to part a btw is 1-3tan^2 theta
http://imgur.com/a/kcX0qsK
Try writing in terms of sine and cosine and put it over a common denominator.
0
4 months ago
#3
this is quite a tricky problem as it assumes you know that cos3theta =4cos^3 theta -3cos theta
Last edited by NatP02; 4 months ago
1
4 months ago
#4
also didnt mean to attach it twice but hope it helps
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4 months ago
#5
(Original post by NatP02)
this is quite a tricky problem as it assumes you know that cos3theta =4cos^3 theta -3cos theta, i wrote out the proof for you
Please familiarise yourself with the maths forum posting guidelines - sticky thread at the top of the forum - in particular with regard to full solutions.

In this case there is no requirement to use that identity.
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